How To Use Your Own Domain on Blogger Blog ?
To buy one, the first step is register on the site where you want to buy (like godaddy.com, doominio.es, cdmon.es, name.com, etc..) And verify that the domain you want is free, ie no one purchased before.
After checking the availability, you can proceed to purchase the domain.
How to change the domain of your own Blogger
The domain registrar once bought yours, will provide a panel with DNS information and other data required to redirect the old domain to the new blogspot. Consult the help section of the site for details, or contact technical support.
Once you have set all this, it’s time to go to Settings your blog on Blogspot.Within this option, select Publish and hit “Change for Custom Domain”, to then access Change to Advanced Options.
And it almost is, write the new address of your blog (now itself without the domain. Blogspot) and tab marks out asking if you want to redirect or not. Latter it will do is that when someone writes your pages without the www at the beginning, to be directed to your blog also.