For a decentralized website (d-web) or decentralized application (DApp), you will upload website files to IPFS network instead of to github or other centralized storage network. InterPlanetary File System (IPFS) is a protocol and peer-to-peer network for storing and sharing data in a distributed file system.
IPFS allows users to not only receive but host content, in a similar manner to BitTorrent. As opposed to a centrally located server, IPFS is built around a decentralized system of user-operators who hold a portion of the overall data, creating a resilient system of file storage and sharing. Your decentralized website will have a unique hash, allowing other peers in the network to find and request that content from any node who has it using a distributed hash table (DHT).