If you have Windows XP, the process isn't too complicated.
--First, save the file somewhere (On your Desktop, in a folder, wherever.).
--Right-click the file and bring your cursor (On the menu that pops up.) to where it says "Open With." A second little menu should appear next to the first. Look for "Microsoft Photo Editor." Click on it.
--Microsoft Photo Editor will open with the selected image in it. Look at the top of the Microsoft Photo Editor window and find the "Image" tab. In the drop-down menu that appears when you select "Image," find "Resize."
--A new little menu should appear. Find where it says "Units:" and look below it. There should be a little box with "Inches" in it and a small down arrow on the right. Click the arrow. You should be presented with three choices. Choose "Pixels." Now your Height and Width are in pixels. Simply change the numbers in the Height and Width boxes to the size you desire and click "Okay."
--Then you can go to the "File" menu (At the top where "Image" was.) and either save the file or "Save As" to save it as a different file.
You are done. If you don't have XP, I probably have to point you to an image editor.
EDIT: You posted this less than two hours ago. It can sometimes take a few hours for a response to threads. Patience is a must.