What is prayer? This is a basic question that must be asked before we can practice prayer we need to know what it is.

A basic dictionary definition.
prayer
prer/
noun
a solemn request for help or expression of thanks addressed to God or an object of worship.
“I’ll say a prayer for him”
synonyms: invocation, intercession, devotion; archaicorison
“the priest’s murmured prayers”
a religious service, especially a regular one, at which people gather in order to pray together.
“500 people were detained as they attended Friday prayers”
an earnest hope or wish.
“it is our prayer that the current progress on human rights will be sustained”

So does this basic definition cover what prayer is?

I found this and like it for a definition:
Genuine prayer has all of the qualities and characteristics of a deeply meaningful conversation between two people. God said to the prophet Isaiah, “Come now, and let us reason together” (Isaiah. 1:18). This image of God and man sitting down together for a good talk is our best image of prayer.
http://www.intouch.org/you/all-things-are-new/content/topic/why_pray_what_is_prayer_for_all_things

Sitting down together for a good talk!  Is it always positive, no not all talks are.  A good talk allows you to express yourself, good and bad, to the other person.  So when we pray we express ourselves to God, when we read His word he express Himself to us.  Sometimes God uses people to speak into our lives.

So if we are starting out and know not what to say to the God of the universe what do we say?  Sometimes nothing at all, sometimes we just need to listen.

Sometimes using something to get you started is a good idea, here is one pattern I have used in the past, ACTS!

ACTS
One structure for prayer is given by the acronym “ACTS”, representing adoration, confession, thanksgiving and supplication (or intercession.) This is one order, where we start off focusing on who God is, and praising him for that. Let’s look briefly at each in turn :

Adoration is to adore God, to worship him and to fulfil the commandment to love him with all of our heart, mind and soul. As we spend time in adoration, we praise God for who He is – our Creator, our Sustainer and our Redeemer. (more about praise and adoration.)

Confession allows us to clear away the things in the relationship between you and God which are displeasing to Him. All of us have sinned. St John writes in his epistle “If we claim to be without sin, we deceive ourselves and the truth is not in us. If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.” (I John 1:8,9)

Thanksgiving. From childhood we are brought up to say “Thank You” when someone does something for us, or gives us a gift. Each moment God is blessing us, every minute we can recall the wonderful things that God has done for us, and the gifts that we have been given. And so, we need to be constantly thanking God for his blessings. In writing to Timothy, Paul makes it clear that we also need to be giving thanks for everyday, worldly things ” I urge, then, first of all, that requests, prayers, intercession and thanksgiving be made for everyone— for kings and all those in authority, that we may live peaceful and quiet lives in all godliness and holiness.” 1 Timothy 2:1.

Supplication or Intercession. Finally we come to ask God for our needs and the needs of others. There are many demands on our prayer time – many topics and issues that we could pray for, so we need to choose, and to be specific.

So if you are looking for a place to start in communicating with God consider the above.  Can you talk to God if you are not “saved”, YES!  He listens to us no matter where we are at, His desire is that we come to know and trust Him, prayer is a gateway to this.

From Executable Outlines:
The Purpose Of Prayer