Step 1 is going to this site: http://www.sp-studio.de/
Once the site has loaded, click on the language of your choice (english for me...obviously)
First up, click on the hat button. I'm not one to wear a hat often, so I tend to skip this step
Next, click on the hair button. Choose the hair type and color that closest portrays yours. I normally stick my hand in a light socket after I wake up, so I chose that one.
Next, click on the eyes button and choose your eye style.
Next, click on the skin button. There are some interesting colors here. Go wild!
Next, click on the mouth button and choose your mouth style.
Next, click on the body button. Finally, you get to stop looking at your naked South Park body.
Next, click on the hand button. I'm not sure you'd want a different color for your hands, but maybe you had a really bad sunbathing accident.
Next, click on the legs button. Gotta cover up those chicken legs!
Next, click on the stuff button. Some fun stuff going on here. Get crazy!
Finally, click on the back button. To complete the look, you should be in your favorite South Park location.