How do I search for books for a certain age group. When I put in YA or ages it brings up text books and such. I don't know authors. I have a little free library and looking for some books in higher age groups, I'm loaded with toddler books

You could search "chapter books"; or when you do a genre search for children's books you can do a second genre for ages "4-8" or "9-12".

You could also look for Magic Tree House, Captain Underpants; Amelia Bedelia, Arthur, Cam Jansen, Junie B Jones are some of the series I can think of. But this age group loves nonfiction too. 

Rush Limbaugh had an American History series with each book about a famous patriot, appropriate for 3rd to 5th graders I think. 
--for early readers try Dr Suess too.  

Have you checked the bookshelf deals in the Book Bazaar forum? One PBS member is offering 8 books for 1 credit.  I think there is a lot of books on her shelf for all ages.

Edited to add: Some titles on her shelf that I have read and enjoyed are: The Treasure of Green Knowe, From the Mixed Up Files of Mrs. Basil E. Frankweiler, The Witch of Blackbird Pond. There are several Newberry Honor Books on her shelf, and the ever popular author Beverly Cleary.