1 Yes it is UML. You can read more (with examples) about class diagrams and other UML diagrams e.g. at http://www.uml-diagrams.org/class-diagrams-overview.html
2 Although it is possible to Google out and print and pin up on your notice board some “
UML cheat sheet” or “
UML quick reference card” (e.g. http://www.holub.com/goodies/uml).
3 it is much better to first read a good book so that you know what is/is_not possible what is the structural/behavioral modeling etc. Explaining UML is not a thing that can be done on 1 single sheet of paper or in one single Stack Overflow answer