How do you repair a fireplace with a rusted-out fire box and then safely install a wood stove?

i am at a lost. i know this is for answers. but i can not find what i need on internet. i have a Woodsman wood stove, it is meduim size, some of the brick need to be replaced but i don't know how to go about getting them out, i read some and it sounded simple but mine does not look that way. Mine at the top of brick has a metal lip that holds them in, i don't know how to get them out or if i did i might not be able to get new ones in. and i can't find it on the internet. can anyone guide me in the right direction.