Hello @xiao,
welcome, if you have questions you can contact me here or even better via @utzer, for general questions you can ask in the !Friendica Support, there is many helpful people there!

For a start it is good to write a post with the tag #newhere (also in your native language if that is not english) and add as many tags as you like with interests, like #biking #nature #hiking or so.

After sending the post you can click the tags as well and follow them (small plus sign in top right), that is a good starting point to find other people of let them find you.

Have fun in the #Fediverse