Last thing - go somewhere there isn't a bunch of car traffic to look out for and run through the entire range of gearing at speed and get a sense for how different combinations affect your cadence/pedaling effort. Look at them after you've shifted up or down and then think about how that feels and sounds. Just remember that your smallest gear is the small (front)/big (rear) combo and vice versa and remember that "cross chaining" is the same/same extreme - big/big and small/small. After you have some sense of what the gearing combos feel like, try to anticipate what gear you need and shift just in advance of need. For instance, when you shifted onto the small ring, your drivetrain was likely close to full-load (pedaling pressure), which is a bad time to shift. You'll sometimes drop your chain doing stuff like this and if you're not quick-witted enough, you're going over
. You need to be pedaling smoothly when you shift, not hammering. Hope that gives you something to go on. Good luck and have a great time with your new bike.
edit: experiment with the forward/back movement of the seat. If you
have to angle it, it isn't the seat for you. Sometimes it's just a matter of moving the seat forward or back so it supports your sit-bones appropriately. Just get on your bike and ride or if you find that too distracting, go somewhere where you can hold onto a wall, and see if you can move yourself into a position on the seat where it feels better to you. Note if you moved up or back to get there, then move the seat accordingly.