Two routers

[rspltd]

Please be gentle with me as my knowledge of computers is extrememly limited. I run my existing computers (upstairs) from a Linksys router which gives me internet and file sharing etc. Because of the construction of my house I have trouble picking up wireless internet and so I want to install a router downstairs to enable me to use my laptop down there. I have installed a router but suspect there is conflict as I cannot get access to the Internet even though my compouter says that I have a good connection. How doI resolve the conflict (if there is one) in simple English please?
Thank you

[wimiadmin]

Is the router downstairs wireless?

Are the computers upstairs wired or wireless?

How is the router downstairs connected to the router upstairs?

[AboveTheLogic]

Disable DHCP and don't use the "Internet" port of the router that is not connected to the modem, just plug the 2 routers into each other using the numbered ports.