calling a html file to a different frame

hello, how am i able to call an normal html file to a different frame from php? Clarification: I got two frames, in the left one you log in, then the database will be connected,in the left frame an navigationmenu will(should) appear, but on the main frame an html file with various things should appear.. so how do i target that file for the "main"frame from within php script? Please help its rather urgent thanks in advance jan