The schematic is just a road map to a circuit. If you begin to familiarize yourself with electronic components the interpretation of schematics will become easier. However until you know what the basic components do and how they modify the flow of electric currents there is no way to interpret schematics. Here is a good website to begin to learn the basics.
The rules are called conventions and are not followed by everyone and in the same way. It will be a good idea to check a variety of sources to see what the conventions are and this will also help you to interpret schematics.
