For this workout, you are doing 2 sets of 5 reps and 1 set of 3 reps. You can either increase the load every set, working toward a very heavy set at the end, or you can use the same load for all 3 sets. Usually, athletes will increase the weight when moving from the 5-rep set to the 3-rep set, but if you are not used to deadlifting, you might want to keep the weight the same for all sets.
Do several warm-up sets before starting your “working sets.”
The weight doesn’t matter if your form is bad. Use the heaviest load with which you can maintain a tight core and neutral spine.