i have to creat a program to convert from miles to killometer and vice versa i think i have writen all the code right. When i got to run it say no main class found ( i am useing netbeans 6.5.1) any ideas
That's not an application but an applet. The two have totally different entry points; applications must have a "public static void main(String)" method.
Try to change the way you want to run your applet; in Eclipse, the Run submenu has several options. No doubt Netbeans does too.