So. Nova Skin makes some really cool Minecraft posters using your skin, or you can upload your own, or choose from their gallery.
Go to http://minecraft.novaskin.me/wallpapers
Select a wallpaper Select one that includes a: Good background and player posture. There are around 70 to choose from.
Select the skin/s that you will use
Select the Download size I recommend 1280 x 720 Also choose an effect if wanted, and choose .PNG
Once downloaded, open a image editing program Use something like Photoshop, Gimp or Paint.NET
Create a new image that is 500X500
Import your poster, and resize it so you can see player skin
Save your image, making sure it is 50KB or under and upload it to Imgur http://imgur.com/
Right click on your image and press 'Copy image URL'
Go to your Mine-imator Forums profile and click on your profile pic, then go to 'Import a photo from URL'
Done. Your profile pic is now complete
I used David's skin for this (Please don't sue me David )