Small CSS Fix up and CMS Update

I have a website which has a customized main page which includes a photo gallery, small news section and custom header. The rest of the site uses a common design. I am having trouble getting the site to only load the main page for the main page, and calling the other design for all other pages. There are also a few other small updates that need to be done to correct a skewed image, and hopefully CSS cleanup so that the site uses a common style sheet.