There is nothing wrong with articulating specific petitions when you pray. We have as examples the Prayer of the Faithful in Mass (right after we recite the Creed), and we have the Our Father (which can be used as a model prayer) and the Hail Mary, both of which ask for specific things. Explicit petitionary prayer is biblical, as this example from Daniel 9 shows:
I prayed to the LORD, my God, and confessed, “Ah, Lord, great and awesome God, you who keep your merciful covenant toward those who love you and observe your commandments!
We have sinned, been wicked and done evil; we have rebelled and departed from your commandments and your laws.
We have not obeyed your servants the prophets, who spoke in your name to our kings, our princes, our fathers, and all the people of the land.
Justice, O Lord, is on your side; we are shamefaced even to this day: the men of Judah, the residents of Jerusalem, and all Israel, near and far, in all the countries to which you have scattered them because of their treachery toward you.
O LORD, we are shamefaced, like our kings, our princes, and our fathers, for having sinned against you.
But yours, O Lord, our God, are compassion and forgiveness! Yet we rebelled against you
and paid no heed to your command, O LORD, our God, to live by the law you gave us through your servants the prophets.
Because all Israel transgressed your law and went astray, not heeding your voice, the sworn malediction, recorded in the law of Moses, the servant of God, was poured out over us for our sins.
You carried out the threats you spoke against us and against those who governed us, by bringing upon us in Jerusalem the greatest calamity that has ever occurred under heaven.
3 As it is written in the law of Moses, this calamity came full upon us. As we did not appease the LORD, our God, by turning back from our wickedness and recognizing his constancy,
so the LORD kept watch over the calamity and brought it upon us. You, O LORD, our God, are just in all that you have done, for we did not listen to your voice.
"Now, O Lord, our God, who led your people out of the land of Egypt with a strong hand, and made a name for yourself even to this day, we have sinned, we are guilty.
O Lord, in keeping with all your just deeds, let your anger and your wrath be turned away from your city Jerusalem, your holy mountain. On account of our sins and the crimes of our fathers, Jerusalem and your people have become the reproach of all our neighbors.
Hear, therefore, O God, the prayer and petition of your servant; and for your own sake, O Lord, let your face shine upon your desolate sanctuary.
Give ear, O my God, and listen; open your eyes and see our ruins and the city which bears your name. When we present our petition before you, we rely not on our just deeds, but on your great mercy.
O Lord, hear! O Lord, pardon! O Lord, be attentive and act without delay, for your own sake, O my God, because this city and your people bear your name!”
The best way to learn to pray is to listen to how others form their prayers. Then just start speaking to God in your own words – Greet him, acknowledge his goodness and power, confess your shortcomings in humility, thank him for all the good he has done for you, and ask him to supply your needs and the needs of those who are on your heart. This is commonly summarized by the acronym ACTS: