Q:

How can I install modules using the FTP method?

I got a error when trying to install modules. What should I set up for the FTP? I just learned Drupal. Who knows what happen? I am using Drupal 7.7.

A:

As kalabro said: 
Make sure the folder /sites/default is OWNED by the user that executes the drupal scripts. 
On most Ubuntu installations, this is the user Apache user www-data.
chown www-data sites/default

A:

Updating modules using that method works only if the server running Drupal also runs a FTP server; in that case, you need to enter the username and the password to connect to the FTP server. The server is normally "localhost" as both the web server and the FTP server are running from the same IP; if that is not the case, then you should change "localhost" with the name of the server (e.g. ftp.example.com).
If you are running Drupal on your local computer, as when you use it as testing site, then if you don't have a FTP server on your computer, you cannot use that way to update modules; in that case, you just copy the files on your computer, after you download the archives containing the updated versions.

