Basically...
Share a gif you just found, and if you don't know how to put one here, just do this:
Step 1:
Press the 'IMG' button on the top of the screen.
[im.g][/im.g](the dots are there for the example)

Step 2:
Copy and paste the link in between your 2 [img]'s.

Step submit and you're done!

It should look something like this:
[img]example.com/example/1[/img]

Here's my funny gif...
[img]a.gifb.in/384yusw280sw.gif[/img]