can i use a second express to increase my signal
can i add a second airport express to expand my internet signal?
Yes, if your "first" AirPort Express is the "n" version of the product.
Check on the side of the device for the Model No in the faint print. You need to see Model No A 1264 there.
If that is what you have, you can add another AirPort Express and use these instructions to configure both AirPorts:
http://support.apple.com/kb/HT4259
The illustrations picture an AirPort Extreme, but the setup for an AirPort Express is exactly the same.