Don't be afraid to ask your pastor or someone else who is spiritually mature if you don't understand something. God doesn't want you to be ignorant of His truth, and they will want to help you. God has given people like this to us "to strengthen and encourage you in your faith" (1 Thessalonians 3:2).
The terms "Holy Spirit" and "Holy Ghost" mean exactly the same thing; both refer to the third Person of the Trinity (the Father, the Son and the Holy Spirit). The phrase "Holy Ghost" is simply an older term that dates back several hundred years, and is found in some old versions of the English Bible (such as the King James Version). Because the word "ghost" has a different meaning today than it did several hundred years ago, modern translations of the Bible always use "Holy Spirit."
Remember that the Holy Spirit is God Himself, and He is at work both in the world and in our hearts. When we come to Christ, the Holy Spirit comes to live within us; in fact, we can't even come to Him until He convicts us of our sins and convinces us of our need to commit our lives to Christ. Jesus said, "When he comes, he will convict the world of guilt in regard to sin and righteousness and judgment" (John 16:8).
But God has given His Spirit to us for another reason: to teach us and open our eyes to God's truth as it is found in the Bible. Is this happening in your life?