Navigate to https://playful-narwhal-8o2zho-dev-ed.trailblaze.lightning.force.com/lightning/page/home

Click on the gear in the upper right hand corner.

Enter the First and Last Name of the user. 

Click the "*Alias" field it is auto populated.  You do not need to enter any values. 

Click the "*Email" field and enter the users email address. 

The Username and Nickname fields are auto populated.  You do not need to enter any values. 

Enter the Company, Department, and Division information. 

If you can associate the user with a Role, pick the specific role for the user.  If the role has not yet been created in Salesforce, "None Specified" is a valid role until one is created for the user. 

Chatter External
Chatter Free
Force.com - App Subscription
Force.com - Free
Identity
Partner App Subscription
Salesforce
Salesforce Platform
Work.com Only
XOrg Proxy User

Select the appropriate license for the user.  Then select the appropriate Profile.  The profile will determine the users Object access. 

--None--
Contract Manager
Custom: Marketing Profile
Custom: Sales Profile
Custom: Support Profile
Marketing User
Minimum Access - Salesforce
Read Only
Solution Manager
Standard User
System Administrator

Populate the users Mailing information if appropriate. 

Select the appropriate Locale settings for the user.  Take into account the users location.  Time Zone, Locale, Language, and Currency will override company wide default values. 

English
German
Spanish
French
Italian
Japanese
Swedish
Korean
Chinese (Traditional)
Chinese (Simplified)
Portuguese (Brazil)
Dutch
Danish
Thai
Finnish
Russian
Spanish (Mexico)
Norwegian

Select a Delegated Approver if needed.  Search for and select the users Manager.  Select the appropriate value for "Receive Approval Request Emails". 

Deselect the "Generate new password and notify user immediately" option if you have another authentication method in place. 

Tip! That's it.  Special attention should be placed on assigning the correct Role, Profile, and licensing.  Local settings are also very important, especially if your work force is spread across the country or in other countries. 

Creating a New User Account in Salesforce.