How do I get the glass block out?

I baught a house that has a garage with broken glass block windows in it. I want to replace them as soon as possible in the most inexpensive way. It is said that you pay people more for labor, so we measured and bought new glass block already incased. I need to break out what is already there before I install the new. My husband has never done this and he thinks he knows what he is doing. I just see a disaster waiting to happen, and maybe an ambulance ride!! Please help!!!!!!!