Im new to this and I was wondering if I can have a different header on each my different pages? and if so how would I do it. Also what is the size I would need so that it matches the raspberry one that came with it.

yes you can, do a search thru the forum, this has been answered a couple times before.

To see the size of the header, look at the header options in the theme, you can set it (or discover it's current setting) there. You can set the image height in the options.

I have used and just tested again the Dynamic Headers plugin. Atahalpa makes this plugin very easy to use. You just install the plugin, replace %image with <?php show_media_header(); ?> in ATA>Style & edit HEADER AREA>Configure Header Area. Then you go to whatever page you want to change the image for and select the picture as outlined in the directions for this plugin. You can choose to have a default image or not in which case there will be no header image. I'm thinking I might make this a default plugin for all my installations.

Thanks for the help I will give it a try