You're new to mastodon and you feel a little lost? Don't worry! I suggest to you to read one of this two short guides to Mastodon:
1. https://medium.com/@GinnyMcQueen/toot-how-to-intro-to-mastodon-e5655bfa87d2, by @GinnyMcQueen.
2. https://gist.github.com/joyeusenoelle/74f6e6c0f349651349a0df9ae4582969 by @noelle