1) Register to
Photobucket.
2) Go to My Albums, and a box will pop up underneath it. It will have many options, click "albums and upload". Click it.
3) Once your there, a blue box titled "Upload Images&Videos", click on that, and a box will come up, and let you chose your photo.
4) Find your screen shot and press "open". Once you chose that file it will automatically upload.
5) Add image name, description, and tags. And click on "return to album".
6) Hover your mouse above that image, then copy the stuff beside "img code:" it will show up as something like this :[IMG]http://i671..ETC.
7) Paste that onto a reply.
8) Profit
(Just incase you can't figure it out, even though you probably can...)