You can invite team members to your Team if you are an administrator on the account.
Step 1: Click on your Team account tab on the website, then click on "Members"
Step 2: Click on "Add team members"
Step 3: Add team member's email addresses. You can also set them as administrators on your Team
Step 4: Click on "Send Invites".
Team members with will show up on the Team tab with their status and permissions. Once they accept the invite their status will change from "Pending" to "Active".
You can also remove members by clicking on the garbage can icon on the right side of the screen