PhysicsAmateur

I have a lab to find the relationship between the two. I know the relationship, but I have to be able to measure the force of tension in a guitar string, or calculate it WITHOUT using the frequency. Is there an equation to solve for string tension where is it set up like a guitar string that I am missing?

If not, if I were to pin a guitar string so that it remains stationary, set it over the pulley, add a weight to the end hanging off of the pulley and add a mass, would the mass provide me the tension as well? Finally, if I were to use this, I would have difficulty getting the string tight enough to produce a frequency. Is there a workaround for this?

Please help, this is been stumping me for the past week.