I find www.photobucket.com (PB) the easiest web hosting pic site around. Open an account (its free) and then select the BROWSE button to look on your computer for a pic to upload to PB. I also like to name my pics on my computer first to make it easy to find with PB. Right click on the pic and select RENAME to do this. When you find the pic you want to upload to PB, just click on it. Then select the UPLOAD button. You will now have a pic on your PB account. Under that pic, you will see 3 boxes/lines, URL, TAG, and IMG. Click on the IMG line and it should highlight, if not highlight the entire line, then right click and select COPY. Go to the board and while posting, just right click and select PASTE.
As for the pic by your name, (avatar) you will need to resize it to the proper size as required for the board. The size can be found on your profile page.