If you want to earn serious income from your blog you should have a top level domain , even you cannot buy paid hosting . Blogger hosted by google, if you purchase with hosting you can use wordpress blog. if you like to buy top level domain and hosting for cheap price you can contact me via our contact us page. I will set up website and i will support you to get extra income from your blog or you can contact my FB page .
When you purchase domain you should have to register CMAEs and A records to your domain DNS tool.
First go to blogger and go to settings edit on the setting mention under your blog address “setup 3rd party URL for your blog” see the image below
After you have Insert your purchased domain address with www.yourdomainname.com then hit save
when you hit save it will not, because you have to submit CNAMEs & A records into your domain DNS tool. just copy the CNAMEs one by one also you can get the IP address for A records just add the IP address for A records in DNS tools,
In the “settings instructions” you can get your IP address.
And go to Domain DNS tools add Records (not Nameservers) insert your CNAMEs & A records into the DNS tools. check the CNAMEs mention below the image,
when you add the CNAMEs & A records hit SAVE settings. now go back to your blogger hit SAVE
Sometimes it won`t allow you to save because the domain wants time for DNS Propagation. It will take only 5 minutes , just leave the page open after 5 minutes try to save again. When the settings succesfully saved you can see your domain has been been Propagated.
If you have still problem with creating custom domain you can contact me, i will help you to fix the problem.