That site is saying you have to do all four options, which will burn approximately 100 calories, then do that four more times, which will burn a total of 500 calories. So your total workout would look like this:
4mph @ 5% for 5 minutes
6mph @ 2% for 3 minutes
7mph @ 2% for 1 minute
3mph @ 10% for 1 minute (set 1 - 100 calories)
4mph @ 5% for 5 minutes
6mph @ 2% for 3 minutes
7mph @ 2% for 1 minute
3mph @ 10% for 1 minute (set 2 - 100 calories again, so 200 total)
4mph @ 5% for 5 minutes
6mph @ 2% for 3 minutes
7mph @ 2% for 1 minute
3mph @ 10% for 1 minute (set 3 - 100 calories again, so 300 total)
4mph @ 5% for 5 minutes
6mph @ 2% for 3 minutes
7mph @ 2% for 1 minute
3mph @ 10% for 1 minute (set 4 - 100 calories again so 400 total)
4mph @ 5% for 5 minutes
6mph @ 2% for 3 minutes
7mph @ 2% for 1 minute
3mph @ 10% for 1 minute (set 5 - 100 calories again so 500 total)