Timthumb Resizing Issue

Alright, I’ve been looking for 3 days for a solution to this problem but I am admittedly new so maybe I’m missing something really obvious. I’m using the Templatic eCommerce theme to set up my web store but when I make a new post the image won’t resize on the home page, it stays the same size and the thumbnail only shows part of the image. At the bottom of every new post there is a little section that says e-Commerce Custom Settings that allows you to put a custom image location in for resizing. Its says “Enter full URL path for image to be used by the Dynamic Image resizer. (including http://). Image must be uploaded to your blog or it won’t resize due to copyright restrictions of TimThumb script. You also need to Chmod cache folder in theme files to 777 restrictions.” I’m changed the restriction and i know for a fact I’m putting the right URL but I’m not really sure on the middle one. I’ve searched every forum known to man to find a solution and if you figure this out you’ll be a hero in my book. Thanks. Also I don’t know if I put enough information, let me know what else you need to know, as I said , I’m new.