To add a new user within your proposal, look over in the action panel to the right where it says, "Default Workflow". If your role within the system is an Admin or a Manager, you will be able to add a new user. Select the blue text/icon that says "+Add User" A pop out will appear in which you will be able to select from a list of Users already in the system or invite a new user by clicking on the blue "+ Invite a New User" at the bottom of the pop out.
After you click "Invite New User" a new window will appear where you will fill in the required fields of First Name, Last Name, Email, and the Role. After you fill in all the required information click "Create User & Send Invite."
The new user will be sent an email inviting them to become a user in your company account. After they register their user account will be ready to go.