C Sharp :: How To Set Rootpath Of Application Which Is Path Of A Selected Item In Listbox

I want to set the rootpath of an executable application. This rootpath should be the same as the path of an item that I select from a ListBox. The code for selecting the item is as follows.

namespace Menu {
    public partial class Form1 : Form {  
        private Button button;
        private ListBox listBox1;
        private string selecteditem;

[Code] ....

Now what I want is: Whatever I get the output as in the :

Console.Writeline(path + selecteditem),

I would want to set this as a rootpath for an application so as to do rest of the measurements or steps only in that path/folder. Is it possible to do something like this?