Now we have received, not the spirit of the world, but the Spirit who is from God, that we might know the things that have been freely given to us by God.
1 Corinthians 2:12 (NKJV)
First of all, we can understand that the "WE" that Paul is talking about here, refers to the apostles and the other authors of the Bible to whom God revealed His word, by the Holy Spirit, to write it down. On the other hand, it is also addressed to us Christians, to whom the Holy Spirit reveals the depths of God's heart and His will.
What God has freely given us is His word. He also gave us the Holy Spirit to teach us and guide us step by step in the process of our spiritual growth. Note, however, that according to verse 14, not everyone is able to understand the things of God, for to them it is foolishness. Only those who have received His grace in Jesus Christ have access to this illumination.
If you are reading this message and you happen to doubt whether or not you have received the gift of the spirit to understand the things of God, you must analyze the state of your personal relationship with Him. If everything is correct, then the next step is to spend time in prayer, asking God to reveal to you what He wants to teach you, so that your walk with Him will be in accordance with His will revealed in His word.