Hello Rega

,
Go to any image uploading website and upload your signature image in that web server. After uloading completes, copy the "Direct Link" (Only the Direct link) and then go to forums and signature settings .
Use [.IMG]your direct link here[./IMG] . Ignore the "." used in the tags..
Click preview to see how your signature would look and if you are happy with it then click apply/submit.
I hope this helps.
Best Regards,
Pr0Ankit