In order to create a quotation or raise a task for a customer you first need to add them to your website as a user. You can have multiple accounts for the same company and each different email address requires a new account. In general user accounts are created automatically when an enquiry is made on your website. But you may need to add them manually from time to time. The video below shows how you can add a user to your website.
Once you have created a user account you can then produce quotations and raise tasks against the account.