https://foodbodsourdough.com/
This is a great site for all things sourdough. My daughter makes sourdough bread every week, and no longer buys any shop bread.
If your friend is giving you some starter, all of the hard work is done; on the day you want to make bread you will feed the starter, and a few hours later when it has got some bubbles, you make your bread. You will leave a little in the jar, keep it in the fridge, and only feed it again the next time you want to bake. If you are not baking, the starter will be fine in the fridge in a screw top jar, even if you go on holiday.
Your friend will also give you helpful advice I'm sure. I am sure that there are many online helpful US sites for advice too.