Press the WIN_Key+R and type in "%appdata%" then press the Enter key. Locate the folder called ".minecraft"and double click to open it. Find the "Saves" folder. (This folder contains all of your Singleplayer worlds.) The folders will be titled after your Singleplayer worlds, the one with the name of the world you have built the map on will be the one you need to upload/give to the admins (when requested.)