a question of python program in the builder console

[njuxyh]

Hi ;
i want to modify the Y  coordinates of 50  atoms which have a tag，for example "selection atoms",
every atom should be added random delta Y  on its original Y coordinate.
i think it is not wise for me to add the delta Yone by one
so it would be done by making a program in the builder console.
i have three questions:
how 'to extract the 50 atoms Y coordinates in builder console? which function should be used?
and how to generate a random number?
and how to update the modify Y coordinates?
I am very sorry I am a newer python programmer. how to use the builder console, would you please give me some hints?


thanks very much