I'm a non-US citizen and I was asked to fill a Form W-8BEN. I googled and I know that there is a tax treaty between US and Egypt but I still don't know the percentage (default tax is 30%). It is also required to specify the type of income and why I should benefit from the treaty. I've never filled a form like that before. So, I would like to know the types of income and reasons to apply tax reduction.
W.r.t. form W-8BEN, the instructions / explanation for the form are here. As far as the tax treaty is concerned, the document is here, and the technical explanation is here. You will have to figure out under what treaty provision you can claim a benefit to put on line 10, or hire a specialist in the Egyptian-American tax situation for figure out how this applies to you.