Error Bars for percentages

Dear All, Firstly I do appreciate your helps on this issue ! Here is my question : Assume for some different values of X which is our independent variable, we have repeated an experiment N times per each X. We will always have m possibilities ( for sure m << N ; in my situation I have m=3 let's say ). So the Y variable which is the dependent one is simply the percentage of each outcome per X. Finally I plotted Y as a function of X for each pathway (possibility). Now I need to locate the error bars on my curves! I wonder if anyone might be able to help me with this issue! I tried to state my problem generally so that anyone can take benefits from the answers! Best, HRJ