Click "Control Panel" link (far left-hand side) on forum menu bar along the top -> Under "Control Panel" area (left-hand side), click "Edit Signature" link, located under sub-heading "Settings & Options".

Upload images for Signature: Yes
Upload animated images for Signature: No
Signature image maximum width (pixels): 500
Signature image maximum height (pixels): 100
Signature image maximum file size: 200 KB

Maximum characters in Signature including vB Code markup: 550
Maximum characters in Signature excluding vB Code markup: 270
Maximum lines in Signature: 7
Allow vB Code: Yes
Allow Basic vB Code: Yes
Allow Color vB Code: Yes
Allow Size vB Code: Yes
Maximum value of x for [size=x] vB Code: 3
Allow Font vB Code: Yes
Allow Alignment vB Code: Yes
Allow List vB Code: Yes
Allow Link vB Code: Yes
Allow Code vB Code: Yes
Allow PHP vB Code: Yes
Allow HTML vB Code: Yes
Allow Quote vB Code: Yes
Allow [IMG] vB Code: Yes
Maximum number of images in Signature: 3
Allow Smilies: Yes
Allow HTML: No