Ok I think I get it. I got a custom map that I played and downloaded from someone elses server.
Then I loaded it in my server (just playing in lan with my son, not stealing it, just liked it) by loading their mod name and loading game then typing /map mp_"mapname".

Now I assume that I can copy any iwd from games I downloaded while playing online to a mod folder that I create, correct?

Next question is how can I get them to all rotate or be listed in the selection window to the right without having to use the console everytime? I downloaded HLSW and haven't figured it all out yet. Though LOL I was able to join a server with my toon on a server I created with same toon so I was in the game against myself essentially. Trippy

you might try adding this to your mod folder ,copy paste on to a notepad then name it config.cfg,remove the txt from the end here you set gametype ,and put the maps you want in rotation ,say remove backlot and put your map name there
make sure you have no extra spaces

// Call of Duty 4
// Public Information
sets sv_hostname "your_server_name"
// Network options
set net_ip "your IP" // Set your servers IP address
set net_port "28960" // Set your port number
// Server Network Mode
set dedicated "1" // 0 = Listen, 1 = LAN, 2 = Internet
//sets rcon for server
set rcon_password "yours"
//******************************************************************************
// First gametype to load
// "dm" - free for all deathmatch
// "dom" - domination
// "koth" - headquarters
// "sab" - sabotage
// "sd" - search & destroy
// "war" - team deathmatch
//******************************************************************************
set g_gametype "war"

//sets map rotation

set sv_mapRotation "gametype war map mp_backlot gametype war map mp_bloc gametype war map mp_bog gametype war map mp_cargoship gametype war map mp_citystreets gametype war map mp_convoy gametype war map mp_countdown gametype war map mp_crash gametype war map mp_crossfire gametype war map mp_farm gametype war map mp_overgrown gametype war map mp_pipeline gametype war map mp_shipment gametype war map mp_showdown gametype war map mp_strike gametype war map mp_vacant"

i run this type of cfg for basic server cfg
if not working when game is running try exec config.cfg in the bottom consule and hit enter "must have rcon password set in cfg and hlsw"
hope this helps