Using a Billion B-7300W as AP

[fromb]

Hi, I have 2 Billion B-7300W ADSL Routers. One is setup as normal and connected to the internet and is situated in my office outside the house. I would like to use the 2nd one as an access point inside the house closes to the office, to pick up the wireless signal from the office router and relay it to the rest of the house so I can use my laptop to connect to that as the signal from the one in the office is very week in parts of the house.
Is it possible to do that without having to run a cable from the office to the house and if so, how do I setup the 2nd router to connect wireless to the 1st router.

Thanks Kevin