Hey Emilia!
Welcome! I think the most important thing to remember is to use /report 1 if you have any questions while you play. A staff member can then help you out!
New players will have a "New player" tag above them, so most people will know that they most likely need to be more patient or offer guidance to you. Don't be afraid to make mistakes!
For commands, you can find a list of these here: https://wiki.eclipse-rp.net/index.php?title=Commands_List
In general it might be fun to go over the ECRP Wiki to learn more about certain faction's, jobs, events, etc!
For things you can/can't do, I think the best I could recommend is to read over our rules page if you haven't already: https://forum.eclipse-rp.net/topic/57059-general-rules/
Just know that it's totally okay to mess certain things up. We always try to educate players, so as long as you try your best and don't deliberately do anything malicious there often isn't much to worry about!
Always ask for help when you are unsure about something through /report or through our Discord, which you can join using this invite link: https://discord.com/invite/y2gxAjg
Hope this helps and curious to see what your experience will be!