I have copied and pasted these two tutorials from another forum I am on hope it helps
OPTION 1
To post images on the forum you first need to upload them to an image hosting website such as www.photobucket.com
Step 1 Register or login to your account
Visit the photobucket website: www.photobucket.com If you already have an account fill in your username and password, then click the 'log in' button. If you do not have an account click the 'join now' button and follow the on screen instructions to create an account.
Once you are logged in, you need to select the the images you want to upload. Click the 'Choose files' button. If you do not see this option then select the 'my albums' link from the navigation bar and it should be displayed.
When you click 'Choose Files' a new window will open showing the files and folders on your computer. Navigate to the photo you want to upload, click on it to select it (it will then be highlighted) and then click the 'open' button. If you want to add multiple photos hold down the Control Key (Ctrl) while you click on the files you want.
To make finding your images easier you can make your files display as images by clicking on the icon circled and selecting 'thumbnails'.
The images you have just uploaded will now be displayed below the upload form. Scroll down the page to view them. Below each image are several boxes with code in which is used to display the images. You need the text in the box labelled 'Img'. Click in the box to highlight the text.
Then right click on the highlighted code and select 'copy' from the options displayed. Alternatively you can select copy from the Edit menu at the top of your web browser.
Open up the post on the forum you want the image in. And right click in the box where the text goes. Select paste from the options. The code should appear.
If you want to check you have done it right, click the 'preview post' button to see how you post will be displayed. Don't forget to scroll down the page afterwards and actually submit your post though!
OPTION 2
Instead of uploading my photos to photobucket or something similar I upload them to my facebook account and then take the photo directly from there to post on to RU. It's very simple but can be a bit confusing to describe without showing you, here is a very basic photo tutorial.
First find the photo you want to post on RU, you can do this on most websites but please don't claim that other peoples work is your own. Right click the photo and it will bring up a menu. Select "Copy image URL" http://i43.tinypic.com/r2ubyp.jpg