Platform series: tutorial 2
This video tutorial will teach you how to make a spritesheet using stitches, and then how to import and setup your spritesheet in GameMaker.
More about Stitches:
Check out Matthew Cobbs awesome spritesheet maker "stitches" at http://draeton.github.io/stitches/. Stitches is developed by Matthew Cobbs in concert with the lovely open-source community at Github. Thanks are owed to the developers at Twitter for Bootstrap, and Glyphicons for some cool little icons. Copyright © 2013 Matthew Cobbs
Any questions, shout out in the comments below.