Very hard to say about the difficulty level with out more information. What is the surface you walk on? carpet? vinyl? tile? wood? ect.. each requires a different process to repair. can you see the frame and sub-floor at the squeak? If so have some one walk on the area while you watch and determine what is making the noise. if its sub-floor rubbing on frame, look for a broken screw and replace if found, inject some glue between the frame and sub-floor, put in a small wedge. anything to stop the movement.
If the noise is coming from between the finished and sub-floors that's a different procedure. but to go further we will need more information.