Welcome aboard! Do you have alternative propulsion (either an engine/motor or paddles/oars)? If so, having someone aboard is less of an issue on a boat that size.
For your first day, pick a day when there is essentially no wind. Go out a bit and drop the anchor (if you don't have a dock). Practice lashing the tiller in the middle of the boat and deploying and retrieving the main sail (the one on the boom). Don't worry about the jib (the foresail, or the sail at the front). For this you'll need to know what the halyard is and where it is on the mast, and where the topping lift is (if the boat has one). Be sure to release the main sheet (the thing that controls the angle of the boom) before you raise the sail. If there is any wind, make sure that you are upwind of the boom. Then push the boom out to one side (or let the wind catch it) and play with the main sheet. Learn how to cleat it off and how to uncleat it quickly. Haul in the anchor, get back to the dock or onto your trailer. If you manage all of that without doing any damage to your boat, yourself, or the other boats in the area, it was a great day. Go celebrate.
The next time, pick a calm day (2-5 knots). Repeat the process above. Note carefully that hoisting the main at the dock can pose problems when there is wind. Get away from the dock, and point the bow into the wind before you raise the sail. Remember to release the main sheet, too, or the boat will heel as you raise the sail. If you feel it leaning a lot, you forgot. Release the sheet and finish raising the sail. Practice sailing across the wind, being sure to tack (i.e, turn the bow into the wind, and you can start this by pushing the tiller over hard so it points at the same side of the boat as the sail). You may make a bit of leeway (i.e., get blown downwind from your starting point) as part of this, but it will keep you in the vicinity of the dock/ramp in the event you have problems. Point the boat back into the wind, lash the tiller, drop the main sail, and head back. If you have accomplished all of this without harming your boat, yourself, or anyone else's boat (or anyone else), then it was a great day; go celebrate!