Write My User Manual

I just acquired a software recently.I need to transfer ownership to another person and I need to make a formal presentation on it's features and program [login to view URL] developer due to language barrier might not be able to provide me with documentation so I;ll need to figure this out on my own.I need a User Manual on this product that will describe the product ,it's features with snapshots of its windows.I want the User Mnaual to be clear ,clean and Orderly with good referencing and [login to view URL] referencing I mean a Menu can be used for each Topic and can be referenced from anywhere on the [login to view URL] manual should be able to teach without the assumption of prior knowledge.