Really n00b question - Downloading resources

Ok so in the resources section, you can download all sorts of models..I'll say one in specific, like the Nazgul based on Fallbeast. It comes as a .zip file to dowload.

I want to ask..

Where do i download this and which folder do i put inside?

Second...

Once I put it in a folder, when i play battle.net for example, will it show up in exchange for another unit?..So I will not have Gargoyle anymore but Nazguls?

Or it onlys show when you play a campaign or custom game by yourself?

Can someone clear this up for me please. There are alot of nice models I'd like to use but I don't know how to implement them and how they effect the game and who they replace.

Thank you guys

For information about how to import a model (when making a map) you should refer to Whitehorn's tutorial: here

Now, as for your question about whether or not the downloaded models will replace the standard ones the answer is no, they won't replace the existing ones as long as you don't replace the models stored in the .mpq files found in your warcraft directory.

If you choose to do so you should NOT play online, as Blizzard most likely will see this (the modification of the .mpq files) as cheating.

If you want to make a map and you want it to feature some customs models just follow Whitehorn's tutorial. The models will only show up in the maps where they have been imported.

Hope this helps you.