newbie question

hello people
i am working with visad since 2 weeks.
at the moment i want to create a grid but i
do not understand the examples in this great
mailing list. i have made a 2d plot like the ones in the first
tutorials of ugo taddei and now i want to make a grid as a
overlay. is there a method or anything like that to use ??

thanks for any help
thomas