Here's a process for you, and anyone else who doesn't know :3 At least, this is the way I do it:
Open the game, and get on your character. Go to a fairly secluded place so that your screenshot doesn't have random people/nametags in it. Put on an expression you like, and press left alt to freeze your character's head. Rotate the camera so that you're facing the head, and press print screen (PrtScrn). Close the game, and open the screenshot in a program like MS Paint. This can be done either by pushing "Paste" in the program, or going File -> Open -> C: -> FeralHeart -> Screenshots, and then locating the picture. However you get the picture opened, use the select tool to make a box around the head/some of the neck. Cut or copy the selection and open it in a new canvas (re-open Paint and paste). Resize the canvas so that there's no white around your headshot, and save the image. Then, go somewhere such as Tinypic, Imageshack, or Photobucket and upload it. Then it's as simple as copying and pasting the image code provided by the website.
Also, I'm working on a banner for us x)