I am looking for my dad and I have no idea how to do it for free. I know that he is either in his late 30's or early 40's and his name is either leonard cooper or lyndel cooper. I never knew him because my mom didn't much either. He was stationed at ft. rucker military base in 1990 and was in the airforce. Any any help would be great. Please id like to know him

Hi, so you have gone through the whole Facebook thing?
I would type in every possible form of his last name and contact everyone you can in hopes of finding a link to him. I have found countless people by searching and finding distant cousins of friends through Facebook.
The fact that you know where he was based is helpful as well, there may be some sort of a record of him and someone may be able to contact him and let him know you are searching for him.