It looks like you're trying to understand how usernames work on Nostr. Let's break it down:

1. **Nostr Identifiers**: On Nostr, users are identified by public keys (npub) and notes are identified by note IDs (note). These are unique cryptographic identifiers.

2. **Public Keys (npub)**:

- For example, `npub1tsgw6pncspg4d5u778hk63s3pls70evs4czfsmx0fzap9xwt203qtkhtk4` is a public key.

- This key is unique to a user and is used to identify them on the network.

3. **Notes (note)**:

- For example, `note1hn9zej2xy8rg826892gale3a8dzftl6fe575v6vdmm9zx58pxkvsacqyh6` is a note ID.

- This ID is unique to a specific message or post on the network.

4. **Using Identifiers**:

- When you see `nostr:npub1...`, it refers to a user.

- When you see `nostr:note1...`, it refers to a specific note or message.

5. **Usernames**:

- Usernames are typically mapped to these public keys for easier recognition. However, the core identity on Nostr is the public key.

Understanding these basics should help you navigate and use Nostr more effectively. If you have any specific questions or need further clarification, feel free to ask!