bubbleman

Hello everyone, i keep having problems when i paste an image that is an abnormal shape or a round shape. whenever i do this i end up with a square white background of the image if you get what i mean. in the old MSpaint there was a couple of icons on the left when you had a selection that would remove the white from the image and make it transperant. any help here would be great if you can understand what i am saying thanks

I was just wondering if it would be possible to put plugins from photoshop into paint.net because my trial version of photoshop has expired and i cannot afford to purchase it and i have quite a few plugins i cant live without!