Scattered around the Map similar to the Missions icons are other icons that indicate Food, Salvage, Lumber, and Fuel and they will have a number near them which indicates the amount of a particular resource that is located there. To begin scavenging tap the icon on the map you want to go to and like the Missions select the party you think will be the most efficient for the task before deploying them to the location to gather the resorces there. On scavenging runs, you won't enocunter any resistance.