How do I make a bridge or doodad walkable?

[Dieseldodge]

Hello there!
I have a little problem:
Example:
I make a doodad bridge but how I make it walkable? I mean not to use the Blizzard Bridges , to create or take one from Structures or whatever it is.
How I make it walkable on ground? Because I want to put it on water and..I have no ideea what to do.

Can anyone help me please?
Thanks.

 

[Tiaan]

Use a blizzard bridge and just change the model/skin to your custom skin/model that you wanted.

 

[Dieseldodge]

Oh , my one can be bigger or etc...Anyway I said doodad , not only bridges..there should be a way..