Avatar control panel
Displays a small graphic image below your details in posts. Only one image can be displayed at a time, its width can be no greater than 80 pixels, the height no greater than 109 pixels, and the file size no more than 6 KB.
For your sig, just check everyone's sig sizes and decide which you like best. I'll check and see if there's a sig size limit.
http://www.thejdm.com/forums/viewtopic. ... size+limit
Quick search resulted in that. Also, you should change the title of this thread to "Signature and Avatar Questions" as the banner (to me) refers to those lame-ass white Hondas at the top of every page.
Note, once you created your avatar you can go into your profile (top of page below lame Honda) and upload it to this site. Your signature will have to be hosted on an off-TheJDM-site (photobucket.com) and then you'll insert the URL into a bar just below where you uploaded your avatar. Change them regularly.