How to post screenies

Well I'm trying to find out how to post screenshots. First I click on the insert image button, But when i press ok it just a x in a box. Can u tell me how to fix this or the real way to post one?

You press prt Scrn. Its right by the scroll lock button(to the left of it). After you press prt screen go to your paint program on your computer and paste it. Then save it and upload it to a picture sharing site like tinypic.com. Once you've uploaded it, copy and paste the pictures url here.

If you didn't understand that than your a dumbass but pm me anyway if you still dont get it