You need to provide the code you (or your friend) already wrote (likely a function file), and describe what you want to do — estimate parameters from data (curve-fitting), optimise your function with respect to specific characteristics or constraints (optimisation), or something else. Asking for ‘a solution for these Nonlinear equations’ isn’t much information, when we have no idea what a ‘solution’ is or what it entails.
What is the nature of the problem are you solving?
