Dividing the windows form into frames

http://www.c-sharpcorner.com/winforms/using_splitter.asp

Using visual studio, drag tree view to the form, set it's Dock property to left. Then drag splitter control next to the tree view, then drag textbox onto empty space to the right of tree view. Set it's multiline property to true, so that it can fill the whole area. Then set Dock property of textbox to Fill. That's it.