A few things,
1) There are already metal railings in Team Fortress 2.
2) If for some reason none of those are satisfactory, you don't really describe what needs to be different from the railings in game.
3) Everyone here uses Hammer, there is nothing else to use to make Source maps with.
I'm guessing your having trouble finding them in the directory. I don't use hammer, but from the the model viewer, they appear to be in a folder called "props_spytech" some with the name "stairs railing" and others with the name "spytech railing".