When you are making a post you will see the icon shown below. Once you click that...
It will bring up a new window where you will want to click on the browse button as shown below.
And that will bring up a new window to select the picture off of your computer to upload to the forums. Select the picture you would like and click open.
That will bring you to the previous screen at where you click the upload button.
Which then will pop up this dialog box at which you just click OK.
Which will bring you back to the following page at which you click on the picture you would like to include within your post and it will show it in the preview plane and then simply click OK and it will insert the photo into your post.
I hope that will help you out, if it doesn't just let me know.