Update README.md

Added Usage section

Author: StarKnightt

README.md

@@ -1,9 +1,12 @@
 ## Calculator Using Java
 This is a simple calculator application written in the Java programming language.
 
-Installation -
+## INSTALLATION -
+
 Clone this repository to your local machine using the command:https://github.com/StarKnightt/Calculator-using-java.git.
 Open the project in your favorite Java IDE, such as Eclipse or IntelliJ IDEA.
 Run the Calculator.java file to start the application.
 
+## USAGE -
 
+The calculator application can perform basic arithmetic operations such as addition, subtraction, multiplication, and division. The user can enter two numbers and choose which operation to perform. The operation's outcome will be displayed on the screen.