Hold the bag up so that the wide end is pointing up toward you.;
,,, Push it onto the end, narrow end pointing down.
, If you're using multiple colors of food coloring, which you probably are, you can separate your frosting into bowls and add the food coloring. Remember only to put in two or three drops of coloring, depending on how dark you want your color. Always try to make a little more frosting than you think you'll need, for each color. It's also a good idea to leave a little frosting white too, just in case.
 There are a couple different ways to do this:


To make peaks, use an open-star tip. Fill the bag and gently press the end of the tip against the cake. Lift the bag up, squeezing the middle of it moderately hard. When you reach halfway up the peak, release your grip on the bag. This will take a couple practice tries but you'll get the hang of it soon, so don't be discouraged.
Making straight lines is completely easy. Just drag the bag gently across the surface of the cake, remembering to keep squeezing the bag. Keep your hand as steady as possible so as to not make the line shaky. Spread a thick layer of light colored icing, preferably white, across your cupcake. Now fit the bag with a #2 tip and a coupler.

Carefully pipe several thin lines in parallel to each other across the surface of the cupcake.
Drag a toothpick perpendicularly to the drawn lines across the toothpick. Don't let the toothpick touch the actual cupcake, just halfway down into the icing. Also, if you want a very swirly effect, you can do the first couple steps up to the drawn lines and then instead of dragging the toothpick across in straight lines, do it in circles or some other crazy pattern.
Prepare the piping bag.
Unscrew the two parts in the coupler.

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Push the large part of the coupler as far down as it will go into the narrow end of the bag.

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Pick up the chosen size of tip.
Finally, to secure the tip, push the smaller part of the coupler down the tip to the tip's wide end and firmly twist the small part of the coupler onto the bigger part through the plastic.

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Fill the bag.
Start frosting.
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