Have you ever asked anyone to pray for you, or a sick relative, or anything of that sort? Maybe your brother lost his job, so you asked people with whom you go to church to "pray for my brother"? That is what Catholics do when we "pray to saints." We recognize that NO ONE on this side of Heaven can do it alone, and so ask for all the help we can get--read the Creed:
And so I ask the Blessed Mary, ever virgin,
All the angels and saints,
and you, my brothers and sisters,
to pray for me, to the Lord our God.
Doesn't get much simpler than that--we recite that every Sunday with the Confiteor.
I pray for God's will to be done. I pray to think of others. I pray for my own spirit to realize there is more to life than myself. I do understand that God's will will be done regardless. It doesn't matter how much everyone prays about a particular thing.
Think about Schivao for instance.. many prayed for her to live... she did not. The purpose of prayer isn't to get what you want.. it's to put yourself at God's mercy.