(C#) How to open a file in my program via drag and "Open with ..."

Windows has a feature where you can drag a file onto a program or shortcut and it will say "Open with (program name)" I want to be able to do this for my program and when I open with a file be able to go to the text editor portion of my program.

string filePath = //Find path of file just opened
form_editScript edit = new form_editScript(filePath);
edit.Show();
Hide();