Hi and welcome to the board. not sure what you mean by a tutorial. If you google 'free pieced quilt alphabet patterns' there are several sites that come up. Some are pieced, some are paper pieced, some applique. Here's one:
http://www.fonsandporter.com/article...-quilt-project
Download one that you like, create the letters and add backing fabric to make up the correct size.
If you want to applique, you can also use a word processing program, bump the font size up, print the letters and use them as your applique patterns. make sure you reverse the letters when you draw them on your fusible!