If my parents router is downstairs connected to a computer and modem and i want my own personal router, how would i be able to hook it up wirelessly?

Can someone explain this to me even tho it might be common sense. If my parents router is downstairs connected to a computer and modem and i want my own personal router, how would i be able to hook it up wirelessly? Would my own router have to stay connected to the modem downstairs or can i move it in my room and use it as a wireless access point? Can two routers even be connected to one modem?