well, from what i see you havent even touched this game yet. so ill list a few things you need depending on your version of the game and if you got entrenchment or not.
1: do you got entrenchment?
2: in the game install directory there will be a tool called ConvertData_OriginalSins.exe and ConvertData_Entrenchment.exe these will convert files from binary to text and vice versa.
3: download this ConvertData GUI. This tool will allow you to easily convert files back and forth to text or binary. all you got to do is change the ConvertData_originalsins.exe or the convertdata_entrenchment.exe to ConvertData.exe (only one at a time, always mark what one is which. also refer to the thred for more info on the tool.
4: thers a file called entity.manifest, this file is located in the entrenchment folder of your sins install (if you use entrenchment) it contains a list of EVERY entity that was added/modifyed by entrenchment, to add new entitys to entrenchment you got to add them here (including updating normal Sins research and whatnot)
5: your mod folder is generaly not visable by searching the normal way. best thing to do is search using windows search really. but if you got no luck there you can always type the command into either the run... program prompt or into internet explorer and hit enter.
6: create a folder with the name of your mod in the mod folder.
7: the layout is either Mods/(modname)/Entrenchment/(Gameinfo, Entity.manifest, other folders with modified information) or just mods/(modname)
8: i havent moded SOASE without entrenchment so i cant give you much support there. as far as i know the manifest is only for entrenchment.
well, hope that helps a little, its really late here and im tired as hell so sorry for any errors in typing or coherency. as for showing hidden folders, go to tools/folder options/view/show hidden files.