How do you change a wireless network into an access point?

I much rather download something than, do it myself, but if I have to I'll do it.How do you change a wireless network into an access point?
If you're talking about the router, disable the DHCP server and connect the modem to one of the router's LAN ports. It should take you about 60 seconds to do both. (Your modem's also a router? Then you're doing the right thing if you want to forward ports, but remember, you now have to forward the pots in the modem, not in the router.)