If you are using FCP (mmmh what software are you using? I noticed that you are on W. XP) use BORIS vector shape filter from filters tab.
Alternatevely create a simple black rectangle in Photoshop, export it to FCP ( use composite mode to get rid of background if you get one) and rotate and resize it in FCP using motion tab tools
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PS. The one above is a quick and general suggestion, post back if you need extra help, one of us will help you.