Blender groups for Babylon.js

[nodejs]

Hello community,

i am new here, because i have any questions about blender + babylon.js
I want to create a game (oh, really ? :D), write the logic in JavaScript and the design stuff in blender.

Now i am an point i dont know how to group objects in blender, so in can use them in babylon.js
I am great in Webdevelopment but terrible in blender (no experience)

I am able to add stuff like tubes, cubes, etc. but not shure about how to group them so babylon.js can create meshes out of the groups.
It seems to babylon.js create for every item (cubes, tubes, ...) i add in blender a new mesh.

I want that when i group things, that only for the group are meshes created. (See screenshot)
BTW i export every thing as *.obj
 

And (for this point not necessary), how can in group, groups to an whole "item", like an building, car, or something else ?

Thanks guys!