Step 1:
Right click the desired siggi or picture you want
NOTE-The siggi or picture should be on the internet not from your PC.
Step 2:
Copy the URL code of that picture.
Step 3:
Click Settings
NOTE- Its on the Top Right Hand Corner of every page when you on IF
Step 4:
Click Edit Profile
Step 5:
Scroll Down to the Signature box
Step 6:
Type this ===>

Step 7:
Type ==>The URL code of the picture
Step 8:
Type ===>


with no spaces or anything!
Ruby!