•You can place window of your application to right of the screen. Then you need to handle events when mouse enters (MouseEnter) and leaves (MouseLeave) the form to move the form up and down.
•You can use a background thread to call GetCursorPos method at a set interval (i.e. each 500ms) second to check where currently the mouse is. See this link for more information about it and a sample code: http://www.pinvoke.net/default.aspx/user32.getcursorpos. (If you need only to check the mouse position, you can use a timer to simplify you application.)
Create a dock like application using C# and wpf
To get sliding effect follow
how to show a window with sliding effect from right to left in WPF
And to position your window:
How to set the location of WPF window to the bottom right corner of desktop?
Moral of the story
Stop asking questions that have already been asked many time.