I would like to know if someone died in my house because a lot of weird things happen in here and I've had a couple experiences that bother me so how do I find out

You can ask old timers in your neighborhood.
If they can give you any specifics like names/year
Then you can go to the library and look up local newspaper articles

How old is your house?

I live in a 700 year old italian palazzo, and I am sure that many people and animals have died here. Remember, just because a building is old, or just because people have died there, doesn't mean that it's haunted. The older the house is, the more unique its structure can be.

Even when people have a haunted house torn down and a new house built there it will very likely still be haunted.
I have heard of people doing that to get rid of the ghosts and it didn't work because the ghosts are not limited to buildings and material things.