It is a good idea to commit as many errors as you can think of with this program, so that you see what error messages the compiler produces. Sometimes the compiler will tell you exactly what is wrong, and all you have to do is fix it. Sometimes, though, the compiler will produce wildly misleading messages. You will develop a sense for when you can trust the compiler and when you have to figure things out yourself.
How many of the syntax rules of Java can you guess just by the error messages from the compiler? If you are ever unsure whether something is legal in Java or not, ask the compiler!