Important: Ensure that User Permission has been already set up prior to this process of allocating user permission to a user. If you have not done it, click this link here.
Step 1: Go to your Dashboard and click Settings. Press User Permissions & Access Levels under People Setup.
Step 2: In the User Permissions & Access Levels page, click the button beside the + sign to allocate a User Permission to a user. When you hover over the button, it shows User Access.
Step 3: In the User Access Levels page, click the plus sign to Add User Access.
Step 4: Select User from the dropdown. Select the Access Level as well. Then, click Save.