Is this a pre-made script or something that you're writing yourself? I'm assuming it's pre-made since you say you're fresh on the scene.
When I first started writing PHP Code it took me a couple of months to really get the hang of some of the more advanced principles of image manipulation and such. My advice to you is to step back a bit.
Try using a home-rolled image uploading script (something you write - even if it's not as advanced as what you're trying to use now - solely for the purpose of learning) so you can get the hang of things and perhaps - if you can write your own code, you may even be able to understand a different coders code.
The link i'm about to post shows one of the first image uploading scripts i've written
http://www.deadlysinx.net/FREE/UPLOAD/
It's about as basic as it gets and may help you understand what it is you're trying to do. I encourage you to take your time and learn whats happening inside the script itself. Once you get the hang of it, you'll likely feel more comfortable writing or editing others more complex code
Image manipulation can be fun, but it can be quite the headache as well. I'm writing a virtual car dealership script and it depends heavily on image manipulation (adding, re-sizing, editing, deleting, writing on images, etc). You can check it out here at
http://www.firststopmotors.com