If you'd like to assign a contact to a new membership follow these steps.
Go to Memberships.
Click the + New button and select New Membership.
Pick the Membership Level
Search for an existing contact or add the membership to a new contact.
You'll see the next screen. You can choose the relevant options to suit.
Select if you'd like to send them a Welcome Email.
Has the contact paid yet?
a) If yes, leave 'Paid' highlighted and select the 'Payment Type'. Tick 'Partial Payment' if the contact has only paid part of the fee. Then select Complete.
b) If no, select 'Needs an Invoice' and tick the box 'Email an Invoice'. Then select Complete.
This will complete the membership for that contact. If you selected 'Needs an Invoice' you'll see that the payment is outstanding and you can add a payment when you receive it.