Assuming your application is in c:\wamp\www\address
A quick and DIRTY way is to
Find out what IP address your wamp server is using
From a command windows on the wamp server PC execute > ipconfig
Look at the "IPV4 Address" this is the current ip address of the pc on you LAN.
lets assume 192.168.2.10
Then just "Put Online" the wamp server.
left click the wamp manager icon -> Put Online
Now you can address your application as
http://192.168.2.10/address
from any other PC on your network
The problem with this is that if your users use
http://192.168.2.10
they can see the wamp configuration page.
They would be able to click on the Projects link that would say "address" ( assuming thats the folder name of your application) to launch your app which is ok i suppose.
They should not be able to play with any of the phpMyAdmin, sqlbuddy etc links as they are protected via other mechanisms and can only be run from the PC running WAMP, but they would see them.
The other problem is that when you reboot your wamp server PC it may get allocated another IP address by your router, most use DHCP to dynamically allocate ip address's as needed and dont guarantee to use the same address for the same pc.
Like i say this is a quick and dirty method. A more secure and stable method would involve making the IP address of wamp server Static ( would need the admin password for your router and a config change to the networking of that one PC )
Create at least one virtual host in apache, 2 would be better and allow you to have a LIVE and DEVELOPMENT version of your app should it ever need modification.
Add specific security to each VHOST folders so all or only specific PC on you lan can use this application.
Leave the WAMP Server offline so that no accidental access's could take place from your network.
Change the hosts file on all the other PC's in the network so that can address your web application with a nice name like
http://client-info.net
just an example.
This would involve a lot more changes and configurations and is open to many more mistakes even when you think you know what you are doing.
I short a full step by step description might take at least 2-3 hours to produce for someone who is a self confessed beginnner.
Of course somebody could do most of this for you using TeamViewer, all the work on the wamp server pc anyway. But you might find they would like paying for it as this is not a wamp problem..
Dont you have a local techy you could get to give you a hand?