5357 posts and you don't know how to manage attachments?!
Click "Go Advanced", beside the formatting options you'll see a little paper clip, click it to upload pictures and stuff... Attachments! Once you've uploaded your stuff, just click the link and copy the address... You know how to post pictures, right?
If you don't know how to take a screenshot, you'll have to take a look at your keyboard... Somewhere near your delete button, you should find a button called "Prt Scr", "Print Screen" or something like that. Press it, then open Paint. Paste. Save. Voila, screenshot!