One of the ways that you can verify your domain name for use with Google Apps is by adding a TXT record in your zone file.

Google will provide you with a code that you will need to add as a TXT record in your domain's zone file. This 'token' is 68-characters long, and starts with: google-site-verification

To add the TXT record you need to first log into your domain's control panel, and look down to the DNS management area:

Click on "Manage your zone file".

You will now see a table presenting your zone file, and three links above it: 'simple', 'normal', and 'expert'. It is actually easier to use the 'expert' interface, so click on that. You will then see something like this (yours will likely be slightly different):

You will now need to add your desired TXT line.

Here is a model that you can follow:

@ 10800 IN TXT "google-site-verification=whatever-google-gave-you"

Simply add your line to the bottom. Of course you need to add the bit between quotation marks with what Google gave you.

When you are done, click on the "Submit" button on the bottom of the page to continue.

All that remains now is to wait for the changed to take affect, so for this please wait at least 3 hours (Google recommends waiting 48 hours before testing).

If you have a Linux or Macintosh, you can test and see if the propagation is complete by using the following command in a terminal/console:

 dig TXT yourdomain.com

If it is done, you'll get a result like:

;; ANSWER SECTION:
yourdomain.com 10800 IN  TXT     "google-site-verification=whatever-
google-gave-you" 

If you are on windows, you'll need to search for a web-based tool that can do this