To add users to your SharePoint site follow these simple steps:

1) Click Site Settings on the SharePoint menu bar

2) Under the 'Administration' area click Manage Users 

3) Click the Add Users link on the bar

4) For Step 1: Choose Users enter the user(s) you want to add separated by semicolons
    (enter each user's email address--SharePoint will email each user his/her credentials)

5) For Step 2: Choose Site Groups check any of the boxes that apply to the user(s) you're adding then click Next

6) For Step 3: Confirm Users double check the user name(s) and display name(s)

7) For Step 4: Send E-mail edit to your liking

8) Click Finish to add the user(s) and send the info email(s)