If you'd like a sense of how a first session could unfold, here's a gentle picture — less a rulebook, more a possibility you can shape to fit yourself. You might find a reasonably quiet spot and settle into a comfortable position, sitting with your back fairly upright, eyes closed or simply lowered and soft. A few slow breaths at the start can help signal to your body that there's nowhere to rush off to.
From there, you could let your breathing return to its natural rhythm and rest your attention wherever you notice it most clearly — perhaps the cool air arriving at your nose, or the gentle lift of your chest. Before long, thoughts will pull you away. They always do, for everyone. The quiet magic is in what happens next: you notice you've drifted, maybe label it softly as "thinking," and guide your attention back without any scolding. That small, patient return, repeated as many times as it takes, is the practice in its entirety.
As for how long, many of the studies that show benefits used daily sessions of roughly ten to twenty minutes — but there's no rule that says you have to begin there. Starting with five minutes is completely legitimate, and gentle consistency tends to matter more than dramatic length. When you're ready to stop, you might take a moment to notice how your body and mind feel, resisting the urge to grade the session as "good" or "bad." There's no scoreboard here.