Help for a beginner to stata

#1
Hi,

Im new to Stata and having trouble with running a loop. I'm studding on export markets and I want to generate a dummy variable so that variable be equal 1 if export_value in 2 years before current year be >0.


I know its something simple but I cant figure it out!

Sorry for bad writing! Beacause I'm not English.

Thanks a lot!