Hello this is a basic overview of the steps you take. You may need to seek hands on assistance from a friend who understands this stuff if you get stuck.
1. ftp all the files from the old server to the new server
2. backup your database and restore it on the new server.
3. Edit your config-inc.php file and change the server path to photopost as well as update the mysql information to that of the new server.
4. You should be able to sign into admin and then you can update the Admin => Global Options to set the correct data and uploads path for photopost
5. Set file and directory permissions per the installation instructions http://www.photopost.com/installphp.html