How Do I Make A Collage On The Computer?

I think you can make it with adobe photosop. There is a tool that cuts peaces of photo and you can add them to another. So i recommend you that program. I have tried it for other things and it was great.

Hmm... You actually ask two different questions there... For making a collage on the computer, any graphic program capable of cutting a controlled portion out of one picture and adding it to another would do fine (and as Razielce noted, Photoshop is terrific at just such actions), but to 'make collages on the internet'... That's something completely different, and I'm not sure I understand...
Are you wanting to make a collage as you are surfing the net, using pictures you find as you go? Or wanting to be able to capture pictures, cut them out as you see fit, then paste them into some sort of on-the-fly updating image on some site you are maintaining? If you could clarify the second half of your question, it would really help.
Otherwise, if you are looking for a 'free' program to do the same thing (as Photoshop costs money, unless you're willing to download a 'pirated' version of it and the appropriate key code), technically, you can use Multiple copies of Microsoft Paint opened at the same time, and simply paste the original image in a separate running copy of paint, cut off the parts you don't like, select just the remaining image and cut or copy it, then paste it into the other version of paint you have running.
...at least I think that will work, I can't test it because I don't seem to have it installed (huh, never realized it)...
Hope this helps in some way. Have a great day!