Is there any way to post artwork on here similar to when you e-mail artwork to someone? If so, I'd love to show someone a drawing I've been working on featuring the stars of Three's Company.

You could upload it to some webhost, and then add a link to the image here using the UBB code:
http://www.sitcomsonline.com/ubb/ubbcode.html

Most of my drawings are jpeg files. Does that affect anything? I also went to the site but I had some trouble there. How exactly do you create a link, and can you use an attach method like with e-mail?

You can just e-mail them to me as attachments and I can post them if you like - e-mail me at todd@sitcomsonline.com