How can I select data, from inside a folder directory, on GUI guide and plot this data?

Hi there,

I would like to plot data using GUI guide on matlab.

I have inside a folder directory, some data points. That in the normal workspace, not using GUI, I plot as follows:

plot(px, pp(:,3,4),'g-','LineWidth',1);
    hold on  
(there are multiple data points)

I would like help on how to access these data stored in the form of workspace.mat in GUI? My goal is to have 3 push buttons on GUI, where I select which kind of plot I want to be displayed.

I also intend to use a pop-up menu to select the different data samples inside a folder directory.

Thank you for the help. I hope I made myself clear, sorry I am new to Matlab and new to GUI.