This is by far the easiest way to post and manipulate pictures.

First go to http://www.photobucket.com and create a free account.

Upload any and all pictures you wish to post to forums, etc....

You can size them to perfectly fit these posts, I believe it's 600x400

Once your photos are uploaded to photobucket, you want to click the Direct Link, it's the second option. It automatically copies the URL or your can highlight it, right click and copy.

Come back to your post and in the spot you wish to insert your picture, click the icon on the tool bar from B I U over to the . Click the and a window will open with a https:// in it, it should be highlighted blue, either remove it or right click and paste. Click okay. Your picture will appear in your post.