discover the frequency of a signal using fft

i need a program to calculate a frequency in a signal. for that i was thinking to apply the fft algorithm. in this first stage i want to take the values of the signal from an excel table. the frequency must be saved in an excel table too(in a different excel file from the input), together with the input values. the output values must be print in a graphic together with the input (in a different color). in this grafhic the x axes will be time (that is supply with the input excel.) after done this i will need to make the same for 5 different values and print the graphs at the same time. all the graph curve must be hidden or not from the graphic (with a check box). this will be not the final program and i think that many complex modifications will be made in the future and i think will be made by the person who start the project. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform windows xp.