Inheritance For Word Pattern

I am in an intro programming class and we got assigned a problem for creating a super class with about a dozen sub classes for generating a random word(via WordGetter class) and then comparing that word to a variety of different patterns(like: does the word contain "re"). We were given the super class which looks like this...

public class Pattern {
public boolean matches(String text) {
return true;
}
public String toString() {
return "(TRUE)";

[code]...

and from this class, we have to write subclasses that override those three methods. I am struggling to understand inheritance and I am not really sure where to even start. Here is the instructions for the first sub class we need to write...

"CONTAINS" SUBCLASS
Constructor: The constructor accepts a String named ‘letters’.

Matches: This pattern matches any text that contains at least one occurrence of each ‘letter’.
toString: produces the text “(CONTAINS <LETTERS>)” where <LETTERS> is the ‘letters’ string.
getLetters(): this method must return letters.
equals(Object): careful on this one. Two Contains are equal if they have the same letters (order is not relevant).
(Example):

Pattern p = new Contains(“re”);
boolean f1 = p.matches(“renew”); // f1 is true
boolean f2 = p.matches(“zoo”); // f2 is false
String s = p.toString(); // s is “(CONTAINS re)”
boolean f3 = p.equals(new Contains(“er”)); // f3 is true.. really..