How do i take my landlord to court to prove reasonable cause to break my lease?

I was living in an apartment where the stairwells were falling apart, literally. the bottom of the stairwell was falling in chunks and the top wobbled. everytime i walk on top of the stairs i felt like it was going to fall from under me. the apartment building was also infested with termites. i had informed them of the problems months before and they said they would fix it but they did not. please give me some input on this. thanks!