Here is how i got sigs to work.
first i copied the sigs i liked to my computer from POF
then i opened user CP and selected pictures and albums
click add album and give it a name like Li's best Sigs
save changes and click upload pictures
browse your computer for your sig and select and open
upload picture and save changes
now select sig by clicking on it and highlight and copy the BB code, it starts with [IMG]
find a thread to reply to, here for example
click reply to thread and write a comment, hit enter to move curser down a line or three and look at the tool bar above your text. I use Align center under font and then Insert Image the little pic of a mountain, this is where the copy of your sigs BB code will be pasted, hit OK. preview post or submit
hope this helps