Here is what you need Zedhe,
Most people think it's fairly easily to create a computer generated drawing or graphics (or web sites), best way to find out is to give it a try.
First, you need a drawing program such as Adobe Illustrator (or comparable software). There are free Open Source software for Mac's, look it up on Google and find a software you are more comfortable with.
Here is a lead,
10 Best Alternatives To Adobe Illustrator http://www.onextrapixel.com/2011/03/15/10-best-alternatives-to-adobe-illustrator/
Once the main drawing is complete (including the rest of the bits and parts you will need) it's assembled with software such as Adobe Photoshop, this software enable the user to create a theme, modify the components to deliver the final results (final Artwork). There are free Open Source software for Mac's, look it up on Google and find a software you are more comfortable with.
Here is a lead,
The 10 best alternatives to Photoshop http://www.creativebloq.com/photoshop/alternatives-1131641
A good free Open Source software for Mac's Photoshop alternative is GIMP http://gimp.en.softonic.com/mac
Now comes the hard part, creating and assembling the final Art work.
As mentioned, most people think it's fairly easily to do Graphic Arts, the reality of the mater is that it takes a good 3-5 years of full time schooling to learn how to use these Graphic Design programs, then it's got to be backed up with a lot of practice (a job in the industry), the creative (Creativity) part can not be learned, it can only be nurtured, either you have it or you don't.