If you have purchased your domain name from SpeedHost.in and would like to use it on your existing blogger account, it is actually quite simple to do.
1) You can log on to your blogger account, from Settings go to Publishing and there would be an option to use your custom domain name. You can read more on this from Blogger FAQ http://www.google.com/support/blogger/bin/answer.py?hl=en&answer=55373
2) You can logon to your advance domain name control panel (your username is the email you registered the domain with and your if you are logging in for the first time, you can use the forgot password option to send the password to your email) Once you are logged in, click on All Orders there you will see your domain name and you can click the domain name. Click the DNS button to make changes to the DNS. Make sure you press the Blue button to change the name servers to the default ones, this will enable your DNS and then you can go on to add custom CNAME records as advices by Blogger.
Please check this link on help with DNS when if you get stuck somewhere while adding A records or cNames.
Once this is done, it my take unto 24 hours for the DNS settings to fully propagate.