Let's assume we have a car frame with tons of spot welds required and we are testing the welds under loads.
The load in consideration is a 250 lb load on the roof. Maybe we are travelling with bags? We defined spot welds using connectors.
You define two sets of spot welds to connect the roof to the side shells. Make sure the spot weld locations are defined and will be meshed. You will have to split the faces at spot weld location.
It is important to define no penetration condition between the parts to ensure the spot weld locations get loaded and the parts generate friction when in contact. The output of this test is a stress, displacement etc.
I hope this helps in understanding spot welds and the steps involved in solving them.