Calling data in a dropdown list

Hi,
I need help with a library s/w. Say I add some authors one by one in one form

In another form I want to add books by each author. So how do I get the author list in a drop down?

And I want to set the status of the books – if they r available, booked by someone or issued. So how can I choose the status from a drop down.

Could some of the you give me the logic for this?

Thanks..