here is a link to the manual where all buttons and functions are explained: http://www.looking4cache.com/manual This manual you can also open in the app in the configuration under the help-section. There are also links to youtube tutorials in the help section.
Yes, you are the blue circle. The arrow on the compass points to the cache or waypoint that is your current target. If the arrow points to the top (green) the target is in front of you. The distance is to the target.
If you hold the button on the right side (to center your position) for a second, the map moves if you move.
I hope this informations helps you.