On the first place you must have the H&D2 Datadisc Sabre Squadron with patch 1.12 installed. Without them you can just forget about any new maps. If you satisfy these two conditions, just download the zipped map archives and extract all folders to your H&D2 directory.
If you want to create servers with these new maps, you have to copy the content of "Maplist.txt" included in the zip archive into "mpmaplist.txt" in your Hidden and Dangerous 2 directory. You however have to make sure that you pasted the new map into the correct map section of the mpmaplist.