setting permissions

Hi Folks-
Newbie here. I recently had WP blog installed and am ready to move on to editing files. I see mention made here of setting permissions to 755 or 777, but my web host only seems to have a permission functionality that features boxes you can check or uncheck. The options across the row to check or uncheck are read, write, and exec, and the column is user, group and other. Am I missing something? I realize I should be asking the webhost, but they are sooo slow and uncooperative most of the time. Any suggestions?