To add your CNAME record (see Google's FAQ on this) 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):

Google wants you to add a new line in there to verify that you own the domain. They will give you something that they call a 'unique string' (in this example, let's say that they gave you googlefffggghhh12345 as your unique string. In this case, you would need to simply add the following line to your zone file:

googlefffggghhh12345 10800 IN CNAME google.com.

Do not forget to add the dot at the end of the line! This dot is important and tells the server when to stop. (Also, no, you cannot use the code in the example provided for your domain ;) )

Your zone file with then resemble (you may/will have other lines that are different - the important thing is that you add your Google CNAME entry to your existing zone file) the following:

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 and then to continue with Google's instructions.

Follow our instructions on creating MX records, and add the following records to your zone file to use Google's mail servers with your Gandi domain:

@ 28800 IN MX 1 ASPMX.L.GOOGLE.COM.
@ 28800 IN MX 3 ALT1.ASPMX.L.GOOGLE.COM.
@ 28800 IN MX 3 ALT2.ASPMX.L.GOOGLE.COM.
@ 28800 IN MX 5 ASPMX2.GOOGLEMAIL.COM.
@ 28800 IN MX 5 ASPMX3.GOOGLEMAIL.COM.
@ 28800 IN MX 5 ASPMX4.GOOGLEMAIL.COM.
@ 28800 IN MX 5 ASPMX5.GOOGLEMAIL.COM.