Luke 11:1-13 Now Jesus was praying in a certain place, and when he finished, one of his disciples said to him, “Lord, teach us to pray, as John taught his disciples.” And he said to them, “When you pray, say: “Father, hallowed be your name. Your kingdom come. Give us each day our daily bread, and forgive us our sins, for we ourselves forgive everyone who is indebted to us. And lead us not into temptation.”
And he said to them, “Which of you who has a friend will go to him at midnight and say to him, ‘Friend, lend me three loaves, for a friend of mine has arrived on a journey, and I have nothing to set before him’; and he will answer from within, ‘Do not bother me; the door is now shut, and my children are with me in bed. I cannot get up and give you anything’? I tell you, though he will not get up and give him anything because he is his friend, yet because of his impudence he will rise and give him whatever he needs.
And I tell you, ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you. For everyone who asks receives, and the one who seeks finds, and to the one who knocks it will be opened. What father among you, if his son asks for a fish, will instead of a fish give him a serpent; or if he asks for an egg, will give him a scorpion? If you then, who are evil, know how to give good gifts to your children, how much more will the heavenly Father give the Holy Spirit to those who ask him!”
Matthew 6:5-15 “And when you pray, you must not be like the hypocrites. For they love to stand and pray in the synagogues and at the street corners, that they may be seen by others. Truly, I say to you, they have received their reward. But when you pray, go into your room and shut the door and pray to your Father who is in secret. And your Father who sees in secret will reward you.
“And when you pray, do not heap up empty phrases as the Gentiles do, for they think that they will be heard for their many words. Do not be like them, for your Father knows what you need before you ask him. Pray then like this:
“Our Father in heaven, hallowed be your name. Your kingdom come, your will be done, on earth as it is in heaven. Give us this day our daily bread, and forgive us our debts, as we also have forgiven our debtors. And lead us not into temptation, but deliver us from evil.
For if you forgive others their trespasses, your heavenly Father will also forgive you, but if you do not forgive others their trespasses, neither will your Father forgive your trespasses.
Regarding repetitions:
[Jesus] went again: and he prayed the third time, saying the selfsame word. (Matthew 26:44)
Regarding repeating prayer:
[The judge said:] I will avenge her, lest continually coming she weary me. And the Lord said: Hear what the unjust judge saith. And will not God revenge his elect who cry to him day and night (Luke 18:5-7)
Pray without ceasing. (1 Thessalonians 5:17)
It is a good idea also to read the Holy Scripture every once in a while, and if you don't understand what you read, ask someone who is Catholic.