I need help with network api on 1.21

[TheWhiteDog9487]

Description

I previously made a mod for Minecraft 1.19 and 1.20 following the Fabric Wiki tutorials and it worked fine.
However, when I migrated it to 1.21, I realised that the APIs regarding networking had changed dramatically and what was on the Fabric Docs and Fabric Wiki was outdated. I found a description of the updates on the Fabric Blog, but I couldn't quite figure out what I needed to do to get my Mod working again.

My Mod looks like this.

1. register a number of key bindings on the client, each with its own individual channel name (for the server to recognise which key was pressed and respond to it).
2. when a key is pressed, send a packet to the server containing the current player's UUID.
3. the server receives it and does something based on the channel name and the UUID in the packet, such as adjusting the health of the player corresponding to the UUID.

The errors are mainly in ServerPlayNetworking.registerGlobalReceiver(), ClientPlayNetworking.send() and ClientPlayNetworking.registerGlobalReceiver(). I'm not sure how to make the changes and I think I need some help.