how to open a dialog that lets me choose objects and appoint as variables or array

I am a novice in scripting.

I need to open a dialog that then lets me choose any number of objects (lines in a sketch, surfaces in a model, parts in an assembly) and assign them to a variable or an array of variables for later manipulation.

I will then iterate through the enumerated variables to derive new geometry from them.

Example is calculating the average angle of a group of lines to a reference line. Choose reference, choose lines, enter -- process the lines, output is one new line at average angle.

thanks for your answer!