Click on the People tab in the left navigation bar.
Under the Members tab and click on “+ Invite people”.
Choose invitation type 'Members/Guest' then click 'Next'
Enter the email of the person you’d like to invite. You can add multiple emails by separating them with a comma.
Click the Send Invitations button.
There are two more ways of inviting people to your workspace:
By typing in their email ID in the Assigned to the field of a task.
By sharing the workspace invitation link.