1. Open the SQL Server Management Studio. Navigate to the following tree, Security > Logins. Then, right click and select New Login.
2. Click on Search > Object Types and check on Groups box. By default, the Groups box is unchecked.
3. In General page, enter the login name. If you are in domain network, please put the domain name as well. The login name is applicable for both user and group. Accept the default values as per screenshot.
4. In Server Roles page, define to which server roles are required.
5. Next, in User Mapping page, define the mapping for the login.
6. Leave the Securables page as default.
7. Accept the default as well in Status page. Once done, you may click OK to activate the new access.