router set up as wifi extender

My neibour have a WiFi network. He allowed me to access his network. But the signal is very weak in my home. I have a WiFi router in home which can be setup in WiFi range extender mode. I don't have a modem at home. Only this WiFi router. If I configure this router , can I connect my desktop PC to this router for accessing that WiFi network. ????
Is it possible without having a modem???