Click the "Add New Proposal" button and give it name. That's basically it.
But here's some background and things that are good to know...
When you first arrive, it looks blank. That's because you have defined any proposals to work on.
When you add a new proposal, you should also give your proposal a description. We recommend including the solicitation number (if any). You might also want to include the client name, either in the proposal name or in the description.
What you put in the title and description is up to you. You have have a long description or a short one. You can edit it later.
What you want them to do is enable people to be able to find and understand what they are working on.