I tried using my facebook profile pic for this forum but it says its invalid.

Would it be possible to fix this?

https://fbcdn-profile-a.akamaihd.net/hprofile-ak-xfa1/v/t1.0-1/c0.13.112.112/p112x112/165089_10150110545127464_2577347_n.jpg?oh=986299e82d4d0ac8d67d45722d73e88c&oe=56784934&__gda__=1450960388_d13dba693071b822def315dfbf685a81

Nope, you need to specify a direct .jpg/.gif/.png, not an url. So upload the image to e.g. imgur to make it show up.