View or add contacts in Teams

To view your contacts, click Calls  > Contacts. Click My contacts and you'll find an A-Z list of all your contacts and a search bar that you can use to find someone specific. If you want to add a new contact to your list, click Add a contact at the top of your list to get started.

If you switch over to your Featured contacts, you'll see a couple of pre-set contact groups: Speed dial and Suggested. To add someone to your speed dial, click Add to speed dial at the top right of your screen.

Source:

https://support.microsoft.com/en-us/office/view-or-add-contacts-in-teams-4828b70a-0194-4272-9895-cfa9468273cf