Create a rectangle selection? Ctrl+D to deselect? Sorry, but that's complete nonsense and clearly you don't know how AE works and what you are doing. Ctrl+D duplicates items and AE doesn't have selections. This very much sounds like you haven't even tried to create a composition and are mucking around in the source footage view, which of course is again complete nonsense. You seriously and very badly need to read the help and/ or watch at least some basic tutorials.