Confused about extending Airport network range

Hello-
I'm trying to extend the range of my home's Airport extreme network using an Airport Express. Essentially, I have two Airport Expresses (both 801.1n models), one of which I'd like to use to bridge or extend the range of the Airport Extreme (1st gen 801.1n). Both of these are in my home, the Express lives on a wall of the house closest to my garage where I'd like to stream airtunes to.

I can easily get the house express to join the network, but I don't think it is extending the range of same, rather just serving as a potential connection point, printer, itunes, ethernet, whatever. The express in my garage seems to join the network as well (green light) but audio will only play for a second or two before cutting out for minutes, then another second or two, then cutting out, etc.

So, how do I use an express to extend my extreme's range? I hope I don't have to connect via ethernet to the base station to do this. I was thinking I had some type of bridge or repeater option. I'm using v5.4.2 of Airport Utility software at it seems like the configuration options have changed/slimmed down from previous versions of the same software.

Thanks for any and all help!
rt

 

Thanks...

I've got that going, and by changing the wireless channel I seem to have fixed the drop outs. Knocking on wood of course...