how do I get pictures added on the left side under my username?
You must be ateast a full member in order to put avatar (image under your name on left side ) .
You will become a full member after 120 days which is like 4 months . however you can buy a full member account .
when you become a full member go to my profile > Forum Profile Information > Avatar . you will see only avatar button if you are a fm member . and can select a avatar of size of 120x80 pixels.
What image file types are acceptable?
File types are, PNG, GIF, or JPEG. You can't have animated GIF though, theymos mentioned it. The max file size is 100KiB. If your picture is too big, you can use paint to edit it to size(resize it).