Need help ASAP with Router and Access Point setup!

Hello all!

I just wanted to ask your expert opinions on setting up an access point I am having severe issues with.

My current setup is as follows (kinda complicated so please feel free to simplify if I did something wrong)

I have a DSL router which I have connected to a router, D Link DIR-655, and since it has 4 ports, I took a wire out of the router and brought it back to a switch (also a D Link) which caters for the wired connections. Because of the location of the router, there was not enough signal strength to go around the house, which is made of concrete. So I bought a TP Link Access Point, TL-WA601G. I got that setup and running with no issues. The ONLY issue I have now is that I can't seem to set a security on my network.

The MAIN issue however, is that there is one area of the house where Wi-Fi is needed, so I went out and got myself another access point, however this time, I got a Linksys BEFW11S4.

I need help in configuring that. Please let me know how I can set all that up. I have one IP (192.168.1.1) which is for the DSL Modem and one more (192.168.0.1) for the wireless router. The TP Link doesn't need an IP, if it needs to be configured, we just attach a LAN cable.

Thanking you all in advance....