Well, the first step is to post in the correct forum. I've taken the liberty to do that.
Step 1 - Attaching pics from your computer. After you've composed your post, go to the bottom of the window and you will see a button marked "browse". Click this button, find the pic you want and open it. Then click "and attachment". If your pic meets the required size parameters, you can then click submit.
Step 2 - Uploading pics from a website. Most of these sites, such as photobucket, allow you to copy the [img] tags and paste it directly into your post.
Hope this helps.