Combining a plot obtained from 'plot' command an the one that I have got using curve fitting app

I have plotted a few spectrums by exporting it from Microsoft Excel using 'xlsread' and then plotting it using 'plot' function on matlab. I have got another plot using curve fitting app. Is there a way to combine both of them into one single plot? If yes, can someone tell me the method to do or specify some code. Version: MATLAB R2015a

[jonas]

The fitting app should give you the fitted coefficeints. Use them to plot the curve together with your data.

[akhila k]

I did get the fitted coefficients. But how can i combine both of them. I generated the code of the fitted graph and included in it my existing .m file. But it's showing an error. Is there any other procedure?

[jonas]

What is the expression that you have fitted? You have any code?