Perform the following steps to create a Region picklist field:
- Go to Setup, in the Quick Find box, search for Users, and select Fields option under the Users.
- Go to the User Custom Fields section and click New.
- Select Picklist as Data Type and click Next.
- Enter Region as a Field Lable.
- Select Enter values, with each value separated by a new line option under Values, and add picklist values for the region and click Next.
- Mark the profiles as Visible to which you want to grant edit access to this field via field-level security and click Next.
- Click Save.