Following on from a request for help in another thread, I thought this could be quite useful here.
To show your own pictures in threads on the forums, your images must be transferred from your computer onto "the Internet". If you have your own webspace (perhaps from your ISP), you can upload images to that space and use the images from there.
If you don't have your own webspace you will need to use an image hosting service. There are several free providers, I'll use photobucket as an example. (
http://photobucket.com/)
Once you've signed up and got your account, you need to browse for a picture to upload on your computer (use the browse button in the "add pictures" box.) Once you've selected the image you want to upload, click submit in the photobucket page, your image will be uploaded and will appear at the bottom of the page.
Your image is now "on the Internet" and anyone can see it, but only if they know its address. The address of the image is something like:
http://i29.photobucket.com/albums/c287/rcnk/3a.jpg
To display images correctly in the forums, the address or URL above needs to be surrounded with image tags of the form:
[IMG]http://addressofyourimage[/IMG]
You can apply these tags using the Img button in the forum page or simply copy the full address of your image, complete with the image tags from photobucket. (Highlighting what you want to copy and using ctrl+C (the control button and letter C pressed together) is a useful shortcut for copying, ctrl+V for pasting). The code you need is the bottom one of the three different types of code shown for each image on photobucket, called "Img", which should look something like the example code below:
[img]http://i29.photobucket.com/albums/c287/rcnk/1a.jpg[img]
Pasting the code (ctrl+V) into the reply box and the image should be displayed correctly, like the example below.
As a personal preference, I would try and keep images less than about 600 pixels wide - that way they're not too wide as to have to scroll the forums horizontally on a standard monitor, and users using slower modems aren't struggling to load big image files.
Hope that's of some use.