Your first casino session

The game is the one you've been drilling. Only the procedure is new:

• Buying in: tell the floor or front desk the game you want (usually $1/$2 or $1/$3 no-limit). Buy in around 100 BB where allowed. You'll get chips at the cage or the table.
• Sitting down: you can wait for the big blind to reach you for free, or post a big blind to be dealt in immediately. Either is fine.
• Acting: act in turn, and speak when in doubt. Spoken declarations ("raise to fifteen") are binding and always safe. If you put chips in silently, do it in one motion. Going back to your stack for more is a string bet, and only the first portion counts.
• The one-chip rule: tossing in a single large chip without saying "raise" is just a call. Announce raises.
• Your cards: protect them with a hand or a chip on top, and never release them face-down toward the dealer unless you're folding, because released cards are dead. At showdown, turn both cards face up and let the dealer read them. Never muck what might be a winner.
• The rake: the house takes a small cut of most pots (often ~5% capped at a few dollars), which is why very small pots are barely worth fighting for live.
• Etiquette: don't talk about a hand while it's live, don't slow-roll a winner, keep big chips visible at the front of your stack, and keep your phone off the table when you're in a hand. Tipping the dealer a small chip when you win a pot is customary in North American rooms.

None of this affects strategy. Most of it becomes routine within a lap of the button.