Read the guidebook or the spec. Or, if you like video, watch an introductory webinar. Learn how to control your security and privacy — over the web, email, push notifications, QR codes, BLE, NFC, message queues, sneaker net... Find libraries or connect with DIDComm's authors.
Application-level decentralized protocols are built atop DIDComm. These support activities like secure chat, verifiable credential exchange, buying and selling, scheduling, escrow, bidding, ticketing, and so forth.