1. Images must be available on the web. You cannot upload photos from your home computer to the board, nor from your password-protected email account, etc. You must set up you own webhosting account (or use someone else's) to display your own images.
2. When posting images from someone else's webspace, you need to have their permission first. It is EXTREMELY rude to create inline links to other people's photos on their servers without permission. If they pay for bandwidth, you are also stealing from them, or at least costing them money, when you do this. Some websites even have protections in place to prevent you from doing so. If you must display other people's images. it's better to download them to your own webspace and link to that.
3. To post an image, simply click the "IMG" button above the box where you type your text. This will cause a bit of code that looks like this to appear in your text:
4. After this, click the "Close Tags" link, which should place another bit of code that looks like this after the image URL:
5. That should do it.