There's many ways to resize a photo but I think one of the easest ways is to go to this site:
Online Image Resizer - Resize digital photo, images or pictures online! Click "Browse" and find the picture you want to resize, then click "Open" Then, in most cases, just check the box were it says reduce to 75% and click "Okay" After your picture is resized you can crop it if you want or just right click on it and save it to one of your folders.
If you have your picture in Photobucket just click on "Edit" above the picture you wanna resize. Then click on "Resize" and you can choose what size to have it resized to, in most cases that would be the one that says "Message Boards"
If you want, after you've resized your photo in Photobucket and you wanna post it, just check the little box under the photo you wanna post then scroll down to the bottem of the page and click on "Generate HTML and IMG code" Then copy & paste the code under "IMG clickable thumbnails for message boards - recommended" to the forum you wanna post it on. Your photo will appear as a small thumbnail picture the will open up to a larger picture when it is clicked on.
I hope this helps you. If you have any problems or questions feel free to PM or e-mail me.