‍click on your name

click on profile

you will now be in your profile...

scrolll down to the blank

Signature：(If it is a image , Please use UBB format)

if you have a online album

go there and copy and then paste

hotlinks from forum one on this list

 if using post image that is

it may be different if you are using another album site

paste it to your profile and this should work

hope this helps

Sharon