How to start programming simple applications?

i'm beginner, i've installed android sdk n eclipse also... i've written co开发者_如何学JAVAde for temperature conversion i.e from Fahrenheit to Celsius but when i run on emulator the calculation part is not working i.e no error in code part n i think its not accepting the input values.... please help me

if you have more than one activity, make sure you mentioned it in the manifest.