Please help

I need some way to boost my wifi signal, what I want to do is get a device that I can program with my computer, then put in a room were my wifi signal reaches and then boost the signal a little further, I have seen boosters and stuff but they look like the signal is only taken from your router were you send your original signal and make it stronger, or you hook to your computer to make it send a better signal, I NEED A MIDPOINT or just a signal booster that you can attach to a Linksys thing with no antennas, just 4 Ethernet ports.