Okay, make sure you click go advanced at the bottom of the page first (next to the quick reply button). Then click the paperclip icon. Now, you need to make sure that your picture doesn't ******* the size requirements that are listed. Browse for your picture and click open when you find it. After you locate it, click upload and wait. Sometimes this can take awhile. When it's finished, it will list your current attachments, so you should see it. Finally, click close window. Complete the rest of your post and the picture should be there.
Now, there are a couple of things to keep in mind:
You can only post a picture in a thread if it's the first post (you created the thread) or you own the rights to the picture. In other words, you just can't post pictures randomly as you please. You're better off posting links instead. If you have the picture on your computer just upload it to a picture hosting site and post the link. Lastly, don't hotlink - it gets the moderators all hot and bothered.
Good luck!
