The red you see is kernel usage. It's showing how much of the CPU is being used to run the core of the operating system. You can turn that off by clicking view and unticking "show kernel times". Here is a site that explains all about Task Manager.
Effective Use of Task Manager
Windows Page File is "virtual ram". Your PC will set aside a certain amount of hard drive space to use as "virtual memory". It runs much slower then physical RAM. The general rule of thumb is to set it to 1.5 X the amount of physical RAM you have. So 1 gig of ram you would set your page file to 1500 megs or so.
You set your page file by
>> right click my computer
>> choose properties
>> advanced, look under performance
>> virtual memory
If you have a relatively low amount of physical RAM to begin with your best option would be to install more RAM. As stated earlier, virtual RAM is much slower then physical RAM.