Well,
A Mod is simply a collection/collation of Addons, Missions, Campaigns and other miscellaneous items all bundled under one grouping.
Nothing more, nothing less.
So you need to build a team of people that can make Addons, make Missions/Campaigns and any other roles required and then go from there.
OFPEC can offer information and tutorials for mission and addon making (that's what we're here for), but you'd have to sort webspace/hosting out yourself.
Hope that helps.