Paint.net Help Needed!

So I have been using it and trying to make my self a cool youtube art picture, I have learned how to use it pretty well but I am asking how do I take like a picture that I have on my computer and put it onto it. Kind of like PewDiePies fabulizer. Like a Chicken With Obamas head with a lightsaber and robot legs.
Someone told me this is possible but I cant seem to find how. >.< Help

What I have done so far.

try using either adobe Photoshop, fireworks, or maybe illustrator.
use loads of you tube and try learn it slowly. you can create layers etc

To make your channel art I used Paint.NET and it seemed to work fine. I'm pretty sure that the icons you are talking about would have probably been made in Photoshop which costs alot. Anyways playing around in Paint.NET will make you better at it but a few tips I can give are.
1. Try different filters and combine them to see what happens.
2. Use the magic wand
3.Use Layers settings to add more depth to your photo

Not everyone can afford those programs.. unless you don't buy it I guess

I used the free trail

I tried something

I dont quite understand what your wanting to do here... are you wanting a static image or a moving one? (.gif)

Maybe try a different font, there are lots available at http://1001freefonts.com/

Also, if you're looking for something a little more powerful but still free, I'd recommend GIMP, which is a downloadable program, or pixlr.com, which is in browser.

Just wondering, how much is photoshop? The one that most people use to do all these cool stuff

You can combine pictures pretty easily. Getting them to look natural takes more time - the longer you spend working on details, the better it will look.