I need VB to scan a .txt for a certain line fo text

then i need to make Num = 1 if that text is there or 0 if not (which i can do, not the question) then if num = 1 print the lines i want and if it = 0 then close and say msgbox "Already set up for use"

so all i need to know is how to scan a .txt for a certain line of text..thanks