How to get rid of rats in the house?

Aside from cockroaches here in our house, my mom and I are struggling because of these house rats. I want to get rid of them. I saw a small rat lastnight and I thought it will going to jump of me. I was so afraid that I almost faint. Actually there were no rats before but now they are here already. My mom bought a poison for the rats but it seems like it doesn't work for us. I really badly need your help guys. I know you've got some bright ideas there. Share it to me. Have a good day! Thanks in advance.