Help installing and configuring an Cisco ASA 5505 firewall?

I’m having some difficulties installing the Cisco ASA 5505 firewall at my company. We had an old firewall (Zyxel) which caused a lot of problems so I was recommended the ASA 5505 firewall from Cisco.

The old setup on the Zyxel was two Ethernet cables: A WLAN cable and a LAN cable. On the back of the Zyxel firewall it was fairly easy because there is only two sockets stating: WLAN and LAN so plug them in and there is connection to the Internet.

But when I’m trying to follow the same kind of pattern on my Cisco I get no connection. I plug the WLAN cable into the port 0 (the outside port) and a cable which runs up to our switch into port 1 (as it state in the manual) but I get no connection what so ever.

Right now, the configuration looks like this:

Internet --> Model --> ASA --> Switch --> PC’s and Servers

Am I missing something? I should say, it is my first time installing a hardware firewall so I might misunderstand something.

Thanks very much for your help.

Sincere
Mestika