Adding the domain account to a security group on the SQL Server computer that has sufficient privileges to log on as a service After reading this article,

http://www.red-gate.com/supportcenter/content/knowledgebase/SQL_Backup/KB200710000173

I have some problems configuring point 2) and 3):

2) Create a SQL Server login that has the ability to backup (and restore) databases (y) by adding it to the SYSADMIN server role.

3) Add the domain account (x) to a security group on the SQL Server computer that has sufficient privileges to log on as a service, etc.

Where can I find detailed instructions/videos on how to accomplish them?

Thanks.
To answer your questions directly:

2) In order to add a login to the sysadmin fixed server role you can utilize ALTER SERVER ROLE ... ADD MEMBER (2012) or sp_addsrvrolemember (pre-2012).  Here would be an example:

exec sp_addsrvrolemember 'yourLoginName', 'sysadmin';


3) Without having to reiterate what's found in the following documentation, take a look at this MSDN reference on the service permissions for each SQL Server service.