Im new to AE cs5 and im getting my head around things.
Iv imported images size 2016x1512 (1.00) when i click on it its fine in the little preview box but when i drag to the composition screen its 75% bigger iv tried everything to get the image to the size of the screen no joy iv tried every compo setting settings still no joy
Imported images come in at 100% scale. That means that a pixel on the footage is equal to a pixel in the composition. It sounds like your images are bigger than your composition. You can either scale them to fit or resize them before they are imported.
These are very basic concepts. You should go through some of the basic workflow and getting started documents available on the website. There's an FAQ and links to a bunch of other resources. You should also look HERE and watch the videos at the top of the page.