You should start by changing your sig to fit in with the site's restrictions.
Signature Limits:
A maximum width of 550 pixels.
A maximum height of 250 pixels.
These include any text in the signature outside images.
Total file size of all images combined must not exceed 50 KB (51,200 bytes).
Any signatures not following these or any signatures with questionable or problematic content will be removed/edited by staff, and you may have your signature editing privileges temporarily disabled if this happens several times.
Then try PMing an admin to ask if they'll change your name for you. But since you only joined yesterday I don't know if they'll do it.
