The right hand side where it says Welcome "Your name"
Navigate to Profile
When you hit profile, you will see three bars on top labeled "Profile Info", "Modify Profile" and "Actions"
When you navigate to Modify Profiles, a drop down menu will come down, go to "Forum profile"
Where it says signature enter [ img ]http://"hyperlink of image here"[ /img ]
to find the hyperlink of image just go to said image right click and click on "Copy Image Url"
Insert that Image Url in between [ img ] and [ / img ]
Done
**Note when you're doing this, there are no space between [ img ] or the [ / img ]. NO SPACES**