QUESTION about filming on private locations? HELP PLEASE



I'm new to film making and I have a big interest in making independent films but there is only so much I can shot in and out of my home. But what I want to know is how do people get access to shooting on private property rather it be in a grocery store or a hospital? If it is just simply by asking the owner or manager, how do you approach someone about it. And if its aloud, are you allowed to show copyrighted material like signs that say Wal-mart? Its just a couple questions that i would really like to know because i want to really get serious about film making. So if anyone knows the answer to any of these questions please let me know.