You can add an image on your question/answer, to add an image follow these steps:
1) Click this link and it will bring up an image of what it looks like when you're about to answer a question. The sixth tab under "Your answer", the one highlighted by a black box is the tab you click when you want to add an image.
2) Once you have done that it will bring up this box (see image).
3) Then you copy and paste the URL of the image you want to post, so for example if I wanted to post a Mewtwo image I would copy and paste the URL of the Mewtwo image I wanted into the box (see image).
4) Click "OK" then your image should be posted on your question/answer (see image).
5) You can then enter an image description if you so wish but it's not really that necessary.
If you want to add an image off your computer you'll have to upload it to the internet first, I suggest you create an account on Imgur. By creating an account on Imgur you'll be able to upload images off your computer to your Imgur account. Once you have uploaded them to your Imgur account you'll be able to add your image to your question/answer using the same 5 steps as above.