just to make things clear. newbies cannot post an image to their post but they can post the link. if they want to bypass that restriction they can buy a copper membership. look here for more information

just to add to OP's guide the two links below are a great way to learn how to adjust the size of an image and how to make an image clickable
Guideline on posting images (with size adjustments), hyperlinks
[Tutorial] How to add image, resize image and make image clickable