DIY messenger bag

This is my first post to this community as I am a new member.  I'm entirely new to sewing and crafting together my own clothes, but i'm sick of retail stuff (bought as is), and besides im a broke college student, so I hope to learn and get constructive critsism from a group where it's not a bunch of older people (AKA a group of my peers).  So for my first sewing project I decided to make a messenger bag.  I could be wrong, but it seems simple enough, but *sigh* I can't find any patterns and instructions.  This is what i'm looking for...

This is a small handbag 9"x 11" with a 24" strap, which is not exactly what im looking for, i want something large, like a full messenger bag.  So if anyone can help direct me in the right direction i would really appreciate it.

PS  If you haven't heard about it check out wickedelements.com !  They have such awsome stuff and they sell all the fabrics they use, so if you like to make your own goth/punk/rock stuff, this site is a must see, they're kinda pricey but i think it's worth it.