Preparing cold pasta?!

Preparing cold pasta?

Hi, doing a buffet and doing some cold pasta for the first time. I need some advice. When you cook the pasta do you let it cool before adding the sauce. By the way the sauce is dolmio stir in. Please help me by answering this question, how do i cook the pasta.

Thanks

P.S the best, most useful answer gets 10 points!!

Cold Tri Colored Pasta Bowl
1 box of tri colored spiral pasta
1 small sweet onion or 3 spring onions & tops-chopped small
1 small green bell pepper-chopped small
1 small can of sliced olives-drained
1 tsp. fresh crushed garlic
1 small jar of pimentos-cubed and drained
2 ribs of celery-chopped
1 large carrot shredded
2 t. Italian herbs
10 slices of pepperoni-cut into small strips
1 small bottle of prepared oil and vinegar salad dressing or Italian dressing.

Cook pasta per instructions-drain--put into large bowl while hot and add all other ingredients--toss well--bring to room temp and chill at least 3-4 hours. This is best made one day in advance. Add more oil if necessary-salt and pepper to taste.