Go for a walk somewhere central. Places that are landmarks in some way are often pokestops where you can collect items like poke balls by spinning the blue circle you see there. You have to be stood quite close by to the stop location.
You should be able to see on the app where your nearest pokestops are. You can touch them and it will show a photo. Head out to a couple of stops. Collect poke balls by spinning the stop on your app when you get there (swipe it) and there are usually a few pokemen at the stop to get you going.
Of course the first thing is to tap on one of the 3 Pokémon that appear and lob a ball at it! Marvel at the virtual reality (my first bulbasaur was hanging off our calendar) and then turn ar off so it's playable!
Thank you everyone. We weren't even getting to the map stage which is , I agree, user friendly and no problem at all. We were doing seemingly endless log ins, sign ups, agree to terms. It took me nearly 20 flaming attempts. But then it started working and dd has really enjoyed. We're going on a last day of the holidays trip tomorrow with family that she doesn't really like so this will help hugely- we are going to an urban area for the meet up.