Welcome to #Nostr

Suggestion:

Follow topics using hastags, type #rockclimbing, click on any hastag and you will have the option to follow it if using the right mobile or web browser client

If on Android,

#Amethyst is an excellent choice, feature rich, supports privacy, tiktok like feeds, multi user, supports Amber (more more security), TOR, private chats, etc.

#0xChat is a good alternative, more like Telegram, including chat groups, channels and voice and video calls, all encrypted e2e

if on iOS:

Enjoy Nostr!