I've been invited by Upwork to interview for an enterprise client. I'm new to Upwork and this would be my first attempt to seek work through Upwork. I've reviewed the freelancer help here and here. I've found plenty of information on the proposal process. However, should the enterprise client accept my proposal, how do I send them my contract?
You're getting a little ahead of yourself. They will send you an offer, and you can accept it. Are you sure it's Enterprise and not Plus? People get these confused. Also, since you are new a lot of invites will be scams, so be smart about interviews and what info you give.