1. Act as the character you create would act. It's a Role Playing game after all, try to keep in character. 2. If you want to do something with your characters's skills, weapons, roll the d20. If you get a 20, you're doing baller, a 1... Big oof 3. If your character's HP drops to 0 you're not dead... yet. You get to roll that d20 a few times to see if they bite the dust or not. Get 3 rolls of 11+ you're unconcious but alive, 3 below 10, its time to make a new character. If you get a nat 20 your character survives with 1hp. At least those are the rules for 5th Edition If you're lucky your club members may give you the Players Handbook, just skim through that if you need to look something up. If not heres a copy: https://thetrove.net/Books/Dungeons%20and%20Dragons/D&D%205th%20Edition/Core/Player%27s%20Handbook.pdf

90% of the time you can do something as long as a. You get a good roll on something, b. Your DM says its okay DnD is quite fun, and I'm always happy to see more people get into this game (that I barely play myself...)