Okay, lately a lot of you have been asking, so here is my in-depth tutorial.
FIRST: Go to either
Photobucket or
TinypicAt Photobucket, Go to create account. Simple stuff. Once you've done that, at the top of the page there will be something that says "welcome, [name]", click it.

After you go to your page, in the center of the top, there will be something that says "Choose Files" click that.

Find your image in the box that pops up and hit open. After it uploads to photobucket, it will be the one in the top left of the latest page of your gallery. Roll over it with the cursor and some tags and html codes will pop up. Click the [ IMG ] tag bar and it should say "Copied", (If not, hit Ctrl C or right click copy), then Ctrl V or right click paste in your post on the forums.

Alternatively you would have gone to Tinypic. There you are going to want to hit browse. In the box that comes up, once again find the preferred photo and hit open. You can then hit upload (tags not required).

You will then be sent to a screen with various tags and html codes, again, you want the [ IMG ] code. Ctrl C or right click copy this, and Ctrl V or right click paste it in your post on the forums.

After doing this correctly, your image should be successfully posted on the forums. I hope my guide to doing so has helped you.