Trying to make family tree and find the history behind the hassevoort's?

i have really no info to start with and no pics just my gramps mom and dad's names and garnys mom and dad! i tryed ansestry.com and nothing! my gramps name is Melvin L Hassevoort and his dad is Henry Hassevoort married to Atta Hassevoort formaly Atta Slagh. Thats all i got can someone help me out or is there somewere i can go to find out? I cant afford to pay someone to do it for me.