Most computers have photo editing software but if you don't, you can use Photobucket to re-size.
Here's the steps directly from their site:
Resizing your photos is easy:
Log into your Photobucket account.
Navigate to the image in your album that you want to resize.
Click the thumbnail to display the full-size view, or mouse over the thumbnail and click Edit.
Mouse over the image in full-size view, and do one of the following:
Select Resize, and then choose an option (100x175, 160x120, 320x240, more options).
