Fix script errors and Firefox Extension

I have the following errors on my website: 1. When uploading picture the script suppose to reduce the picture, but is not doing and I getting the error below: Fatal error: Call to undefined function imagecreatefromjpeg() in /home/mydomain/public_html/configfolder/[login to view URL] on line 106 2. The content area of the website do not display when using an address without the "www." For example, This URL works [login to view URL] The same URL without the www. does not work [login to view URL] 3. I have a Firefox extension that needs to be remain and fix because there is one particular page on the website that is provoking conflict with this extension. The error says "Please login" when I suppose to be login. The Firefox extension lets users submit websites without having to visit My Website. You must know how Firefox extensions work. Details of my website will be sent to the winner after acceptance. The work must be completed as soon as possible. I will NOT pay in advance. The payment will be sent after the project has been completed.