Can't help you with how to create but can help with size and how to post.
from the TOS page:
You may include a small personal or business logo/avatar for use as part of your signature. Logos/avatars may not be placed within the body of a message. Any graphic/image used as part of your signature must be 170x50 pixels or smaller in size - no exceptions. Determining acceptable sizes for odd graphic/image shapes not strictly 170x50 is thus: width x height when multiplied is 8,500 total pixels or less. Example of an acceptable size: 125 x 65 = 8,125 pixels. Example of an unacceptable size: 100 x 90 = 9,000 pixels. A pattern of repeated inclusion of a particular graphic/image within the body of a message may be taken into consideration when determining if it is being used as a personal logo/avatar or not. Business logos/avatars may not include specific items for sale, prices, advertising slogans, or other text within them that is generally commercial in nature.
to edit your sig file, scroll to the bottom of any forum page and click on user prefs. Sig file is at the bottom.
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Thanks,
Dave Colling
www.rainbows-r-us-reptiles.com
0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)
LOL, to many snakes to list, last count (02/01/2010):
42.61 BRB
27.40 BCI
And those are only the breeders 
lots.lots.lots feeder mice and rats 
