To Scavenge/Search for Items, click on the item
Usually there will be a blinking white lined cursor surrounding objects on the map that definitely hold an item that can be looted, scavenged, etc. For TUMBLRFan's first item, I clicked on the white car identified in the prior post and pic. The car contained something my character can use for a weapon - a baseball bat.
The red indicator bar is almost all the way over, filled in to the right, so this bat is in good shape for a while.
As items wear out, the indicator bar will show less red and you'll either have to discard the item to pick up a newer, better one or you'll have to find a place (or credits) to repair your weapon.
This bat will not require repairing for quite a while, so collect it (click on it) and it will go into your "inventory" of items.
You'll see a timer on every item you scavenge for. The game re-spawns items according to the timing you see. You won't get anything again from the white car until the "Updates in" timer counts down.
You can search again, using 10 credits (green sigh with coin stacks and number indicating how many credits this action/item costs) but really it's not worth it in the beginning of the game to spend credits. You'll come across tons of map squares that have the blinking white cursor, indicating that items can be scavenged and searched per square.