Q:

TikZ: best way to draw a user guidance

I have a string in the form of .[field].[field].[field] where each [field] needs to be replaced with user specific information. I would like to create some sort of instruction/guidance on what specific information is needed in each field.
My ideas (sorry for the poor drawings):

1st example:

2nd example:

I don't know whether this is the best way to do it, but I think some visualization will help the user to understand better than a block of text (the users are ordinary people).
How can I create such a diagram as seen above using TikZ? I've been playing around with nodes and paths, but I did get really far as I have not been using TikZ a lot. Any help is appreciated!

EDIT:
Thanks to Gonzalo Medina for providing the two examples. I made some changes to it, here's my final result:

\documentclass[dvipsnames]{standalone}
\usepackage{tikz}
\usetikzlibrary{backgrounds,positioning}

\newcommand{\intval}[1]{\textbf{\color{RoyalBlue}#1}}
\tikzset
    { field/.style  = { draw=RoyalBlue, minimum height=20pt }
    , pdval/.style  = { draw=black!10, font=\strut\LARGE
              , minimum height=20pt, text depth=-2pt }
    , dot/.style    = { fill=black, circle, anchor=south
              , inner sep=1.2pt, xshift=-5pt, yshift=3pt }
    , desc/.style   = { fill=black!10, rounded corners=5pt, inner sep=5pt }
    , num/.style    = { draw, circle }
    }

\begin{document}
\begin{tikzpicture}[node distance=10pt, scale=.8, transform shape]
    % fields
    \node[field,text width=60pt]            (user)      {};
    \node[field,right=of user,text width=30pt]  (year)      {};
    \node[pdval,right=of year]          (function)  {st};
    \node[field,right=of function,text width=20pt]  (realm)     {};
    \node[pdval,right=of realm]         (entity)    {foo};
    \node[pdval,right=of entity]            (school)    {bar};

    % dots
    \foreach \n in {user,year,function,realm,entity,school}
        \node[dot] at (\n.south west) {};

    % numbers & descriptions
    \node[num,above=4cm of user.west,xshift=5pt] (user_num) {\textbf{1}};
    \node[desc,right=5pt of user_num] ()
        {Your \textbf{username}, f.e. \textit{foobar}};

    \node[num,above=2cm of year.west,xshift=5pt] (year_num) {\textbf{2}};
    \node[desc,above=5pt of year_num,xshift=7pt] ()
        {Your \textbf{year of joining}, f.e. \textit{2012}};

    \node[num,above=1.5cm of realm.west,xshift=5pt] (realm_num) {\textbf{3}};
    \node[desc,right=5pt of realm_num,yshift=30pt,text width=5cm] ()
    {
        Your \textbf{realm}:\\[10pt]
        \noindent
        \begin{tabular}{@{}ll}
        Architecture            & \intval{A} \\
        Constructional engineering  & \intval{CE} \\
        Chemistry           & \intval{C} \\
        Digital technology      & \intval{DT} \\
        Telecommunication       & \intval{T} \\
    \end{tabular}
    };

    % lines
    \draw (user_num.south)  -- ([xshift=5pt]user.north west);
    \draw (year_num.south)  -- ([xshift=5pt]year.north west);
    \draw (realm_num.south) -- ([xshift=5pt]realm.north west);
\end{tikzpicture}
\end{document}

A:

One option for both alternatives:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}

\tikzset{
descr/.style={
  fill=gray!30,
  text width=#1
  },
field/.style={
  draw,
  text width=3cm,
  minimum height=15pt
  },
dot/.style={
  fill=black,
  circle,
  inner sep=1.2pt
  },
number/.style={
  draw,
  circle,
  minimum size=20pt,
  font=\Large
  }      
}
\begin{document}

\begin{tikzpicture}[node distance=1cm and 10pt]
% the field nodes
\node[field]
  (left) {};  
\node[field,right=of left]
  (middle) {};
\node[field,right=of middle]
  (right) {};
\node[right=10pt of right.south east,anchor=south west,inner sep=0pt,font=\LARGE]
  (foo) {foo};
\node[right=10pt of foo.south east,anchor=south west,inner sep=0pt,font=\LARGE]
  (bar) {bar};

% dots between the fields
\node[dot,xshift=-5pt,anchor=south]
  at (left.south west) {};
\foreach \Nombre in {left,middle,right,foo}
{
  \node[dot,xshift=5pt,anchor=south]
    at (\Nombre.south east) {};
}    

% the boxes for the descriptions
\node[descr=8cm,above=6cm of left,anchor=south west,xshift=10pt]
  (lefttext)
  {Some descriptive text for the first field and some more text and some more text and some more text};
\node[number,anchor=east]
  (leftnumber)
  at (lefttext.west) {1};
\node[descr=4.4cm,above=4cm of middle,anchor=south west,xshift=10pt]
  (middletext)
  {Some descriptive text for the first field and some more text and some more text and some more text};
\node[number,anchor=east]
  (middlenumber)
  at (middletext.west) {2};
\node[descr=4cm,above=2cm of right,anchor=south east,xshift=-5pt]
  (righttext)
  {Some descriptive text for the first field and some more text and some more text and some more text};
\node[number,anchor=west]
  (rightnumber)
  at (righttext.east) {3};

% the connecting lines
\foreach \Nombre in {left,middle}
  \draw (\Nombre number.west) -| ([xshift=10pt]\Nombre.north west);  
\draw (rightnumber.east) -| ([xshift=-10pt]right.north east);  
\end{tikzpicture}

\vspace{1cm}

\begin{tikzpicture}[node distance=1cm and 10pt]
% the field nodes
\node[field]
  (left) {};  
\node[field,right=of left]
  (middle) {};
\node[field,right=of middle]
  (right) {};
\node[right=10pt of right.south east,anchor=south west,inner sep=0pt,font=\LARGE]
  (foo) {foo};
\node[right=10pt of foo.south east,anchor=south west,inner sep=0pt,font=\LARGE]
  (bar) {bar};

% dots between the fields
\node[dot,xshift=-5pt,anchor=south]
  at (left.south west) {};
\foreach \Nombre in {left,middle,right,foo}
{
  \node[dot,xshift=5pt,anchor=south]
    at (\Nombre.south east) {};
}    

% the boxes for the descriptions
\node[descr=8cm,above=6cm of left.west,anchor=south west]
  (lefttext)
  {Some descriptive text for the first field and some more text and some more text and some more text};
\node[descr=4.4cm,above=4cm of middle.west,anchor=south west]
  (middletext)
  {Some descriptive text for the first field and some more text and some more text and some more text};
\node[descr=4.4cm,above=2cm of right.west,anchor=south west]
  (righttext)
  {Some descriptive text for the first field and some more text and some more text and some more text};

% the connecting lines
\foreach \Nombre in {left,middle,right}
  \draw ([xshift=10pt]\Nombre text.south west) -- ([xshift=10pt]\Nombre.north west);  
\end{tikzpicture}

\end{document}

