Hi there,
You need to use the EchoSign API and some dev skills to do this. See the dev center
APIs for signing online, application integration | Adobe EchoSign
Ideally you create your agreement with the API, be it a widget or regular agreement. When creating the agreement this way you can setup a callback url which pings your the specified url each time the Agreements updates. So when the signers signs you get notified and you can use this as a tigger to call the getDocument method to get the signed document and store it in your database.