Alpha Patterns are conducted a little differently than regular patterns. They are made constantly tying one long string on top of a collection of other strings. They are great for spelling out names and making shapes.
The biggest difference between regular patterns and alpha patterns is that alpha patterns don't use forward or backward knots. Instead they consist of downward knots. when the background string is moving to the right, you tie a right downward knot. When it is moving to the left, you tie a left one. If you want to start working on the letter/picture, you would tie that string over the background string in the opposite direction the string is going. So for example, if the background string is going to the right, you would tie your letter string over the background string with a left downward knot.
So those are the basics of alpha patterns. There are patterns all over the internet for whatever type of design you want. So go out there and start looking. For more information of alpha patterns, check out the in-depth tutorial on friendship-bracelets.net.