How can I change the size of my picture?

I am trying to post 2 pictures on justin.tv but it has to be a certain size to work. I want to post a header image which needs to be 950px wide and less then 3mb, and a default picture for my profile which needs to be 640px wide and 480px tall. Also needs to be less then 3mb. So, how do i do it?How can I change the size of my picture?
You need an image editor program which will allow you to scale the image and save it as a new file, preserving your original. (Always save the original! You can scale an image down, but when you try to scale it back up you lose a lot of image quality.)



You don't say what OS you're using, so I can't be specific. You may already have a program on your machine that will allow you to resize (scale) images. I'm not a Windoze user, but I think it comes with one.



If you don't have an image editor already (e.g., Photoshop, GIMP) you can download GIMP here: (http://gimp.org/) for just about any OS. To scale an image in GIMP, you just open the image (File-%26gt;Open), click Image-%26gt;Scale, set the width you want, and click Scale. When you're done scaling it, click File-%26gt;Save As to save it to a new file name/location.How can I change the size of my picture?
Photoshop, any version. Go to: ';image size'; and ';canvas size'; to set how high and wide will be. Then, when you click ';save as...'; you will be asked whether you want to save it as a good quality picture (more MBs) or worst quality (less MBs)