If you want to sign a document, and you want other people to sign it as well, you'll want to start by clicking Sign or send from your dashboard.
After you've uploaded the document that you want signed, you'll need to add additional signing roles to the document so that you can list each signers' name and email address, as well as your own. You can add additional signers to the document by clicking the "Add Signer" field below the name and email address fields. You can have up to 20 signers on one document.