How to run multiple tests on different browsers simultaneously using selenium webdriver?

How to run multiple tests on different browsers simultaneously using
selenium webdriver?

How to run multiple tests on different browsers simultaneously using
selenium webdriver ?
I am working in java, I even tried selenium grid Downloaded: the
selenium-server-standalone-2.33.0.jar file
Even after the procedures,
I am not able to execute these commands on the command prompt
java -jar selenium-server-standalone-2.33.0.jar -role hub -port 4444
java -jar selenium-server-standalone-2.33.0.jar -role node -hub ...
Any other alternative ??