Selecting/Combining problem

[ToxsikZombie]

I'm quite new to paint.net and I have a question about something...I downloaded it so I could "Morph" Pokemon sprites. There's vids of it on Youtube of people doing it on MS Paint. Now, the problem I'm having is with the selection tools. In the "old" Paint, when you selected something, you could make it so you just make a square around it, and you could press a button at the bottom of the tools screen to make the white around it "disappear" or become transparent, so when you out it on another image, the white background wouldn't overlap the other picture. I can't find an option such as this and it's frustrating to carefully trace out the part of the picture that you want to put on top of the other one, only to mess up, and have to start over. So is there a button such as this? Or an easier way to select parts of images without the selecting the background? Oh, and I do know about the magic wand tool, but it doesn't always work. I have played with the tolerance button, but it either selects the whole sprite, or just a certain colored section of the sprite. Here's an example. I wanted to take one of the ears off of 1 Pokemon and add it onto another, if i use the square selection tool, it takes the ear and the background with it and when i go to add it onto the other Pokemon, it leaves me with a white space covering up parts of the other sprite. The ear itself is a long oval shape and has a yellow stripe halfway down it, the magic wand only selects the yellow part, the top half of the ear, the bottom half of the ear with the rest of the body, or all of the pokemon. Please help me! D:

[Ash]

Search for "cutting out images" or "Alpha mask"

And paste it on a new layer.