Digi has provided a software tool to configure all XBee modules. It's called XCTU. It can be downloaded from https://www.digi.com/products/xbee-rf-solutions/xctu-software/xctu. Download the version for your OS platform. Here's what it looks like:

Make sure all XBee modules have installed the XBee Digimesh firmware in order to build a mesh network.

After the XBee module is attached to an XBee breakout USB and connected to a computer, you can add it to the XCTU application. If you have an XBee series 1, you should update your XBee modules with XBee Digimesh. Select the latest firmware for the XB24-DM firmware model, as shown in the following screenshot, on the updated firmware dialog:

Installing Digimesh firmware on XBee modules has its benefits. We don't need a coordinator in a network. We only need to define our network ID for network identity.