If you can't afford Adobe Photoshop, you can download the trial version (
http://www.adobe.com/cfusion/tdrc/in...shop&loc=en_us) and do the following:
1.) Open the file in Photoshop
2.) Go to File > Save for Web Devices
3.) Select which file extension you want: .gif, .jpg, .png8, .png24
-You can select each one and look at the bottom left of the preview screen to see how big the file size is and choose the one that works for you
4.) Click the OK button
5.) Save the file to the folder of your choosing
Hope this helps.