Update README.md

Added background and example

README.md

@@ -1,2 +1,25 @@
 # kiwi-java
-A line for line Java port of the Kiwi C++ implementation of the Cassowary constraint solving algorithm
+A Java port of the [Kiwi](https://github.com/nucleic/kiwi), a C++ implementation of the Cassowary constraint solving algorithm
+
+## Background
+This project was created by porting [Kiwi](https://github.com/nucleic/kiwi) line for line to Java. The objective is to create a faster Java implementation of the Cassowary constraint solving algorithm.
+
+## Example usage
+
+        Solver solver = new Solver();
+        Variable x = new Variable("x");
+        Variable y = new Variable("y");
+
+        // x = 20
+        solver.addConstraint(Symbolics.equals(x, 20));
+
+        // x + 2 == y + 10
+        solver.addConstraint(Symbolics.equals(Symbolics.add(x,2), Symbolics.add(y, 10)));
+
+        solver.updateVariables();
+        
+        System.out.println("x " + x.getValue() + " y " + y.getValue());
+        // x == 20
+        // y == 12
+
+