Fireplaces, Heating Stoves, Flues and Chimneys - My firebox is damaged, please help

I just bought a house with a wood buring fireplace. (Never had one before.)THere is a large crack/whole in the rear of the firebox about the size of a softball. The story I got is that the man who owned the house before me put an un-opened can of beans on the fire and it exploded causing damage to the rear bricks. About 10 bricks in total are affected. I would like to remove and replace the damaged bricks. It seems like a simple job, right? or wrong? Any advice?

Additionally, how can I tell other than by visual inspection whether the explosion caused damage to the chimney and would be safe to use once I have repaired the firebox? What material is the inside of the chimney usually made from, metal or brick? Your help and response is appreciated.

Welcome to the forums! I never want to discourage anyone from doing things themselves, hence DIY. But, this is not a DIY area, unless you have extensive experience in doing it. Call in a pro and let them give you an analysis of what happened and what it will take to repair it. A damaged fireplace must be taken care of before you build a fire in it. Visit again, and let us know how it goes, and if we can help any further with this, or any other project.