Thank you for reaching out. If you want to create an agency to help market the services of a team you’ve created, you’ll first need to create a freelancer account for the person who will be the agency owner.
Once that account is activated
Go to Settings > Contact Info
Scroll down to Additional accounts
Select New Agency Account
After you create your agency, the Account Menu will be where you can switch between your personal and agency account views. A person can only “own” one agency on Upwork. You won’t be able to make another one.
Here's also a list of articles you may need to read if you plan on putting up an agency.