Find a block or stack a couple of 45's on the floor and sit down on a bench. Grab a dumbbell and prop it up on your leg.
Now do a "muscle round" for the sets and reps. This is how a muscle round works for stimulating muscle growth. You'll do 4 reps, then rest 10 seconds. Do 4 more reps, then rest 10 seconds. Do this a total of 5 times. Then on the 6th time around, do as many as possible. Each time you do reps think of that as a round.
For the seated dumbbell calf raises, this is simple. You do the left leg for 4 reps, then you switch to the right leg and do 4 reps. Back and forth, no rest between the mini-sets. On the 6th mini-set, crank out as many reps as possible. These are money.