Enter using SSH into your node and edit lnd.conf

Add these 4 lines at the bottom:

[wtclient]
wtclient.active=true
[watchtower]
watchtower.active=true

save & close the lnd.conf file (CTRL+X)
run docker-compose restart lnd
At this point, your node is running the client & server.

To get your WTClient address run this:

docker exec -it lnd lncli tower info

To add some else's node to you, have them run that command above (on an umbrel) and get the "uris" value, and you run this on your umbrel:

'docker exec -it lnd lncli wtclient add'

(and before you press return, add their "uris" value. it should look like this:

e25b281e05320d83b58....... @qxyhqlor3wqnys7zajalxy5smfapdi7qd........... onion:9911

Here is a list of altruistic nodes that offer WT services for your node:
https://github.com/openoms/lightning-node-management/issues/4