hell-o
cpanel is supposed to facilitate the default file and folder permission on install. at a minimum to get things to work double check that the store folder is at least 755 and the store manager folder is 755. then check the agora.cgi file. should be 755 and the store/protected/manager.cgi is 755 as well.
if you find any of these file's permissions or folder permission are wrong then go here:
http://www.agoracart.com/help/wherestuff.html
and choose the store closest to your version and double chack all files and store folders have these permissions. in most cases you don't need 755 for images ( i think the examples at the link list them as such).
if file permissions wont help then move the store by means of your cpanel to your cgi-bin. try it there.
regards,
dan