Friendly PSA from your neighborhood sports medicine Healer: if you've never ridden a skateboard, it isn't the day to start with one that pops in from nowhere and is right mouthy. Something tells me someone might be filming you from behind a bush.
If someone is mechanically inclined, perhaps it might be a good time to set up a half-pipe in one of the parks. I know that's more or less a Muggle thing, but I saw it many times when I was in the US. It will be better than scraping your knees because the skateboard doesn't like a cobblestone or two.