Joh 16:13 Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come.
14 He shall glorify me: for he shall receive of mine, and shall shew it unto you.
All Christians are indwelt by the Spirit of the Lord. Romans tells us that if we don't have the Holy Spirit, then we are none of His.
However, being filled with the Spirit is another thing. There is ONE baptism of the Holy Ghost, but MANY fillings.
Few Christians that I know concern themselves much with being filled with the Spirit. They are content to swim in peanut butter rather than be empowered by God's Spirit. Have you ever driven an old vehicle without power steering? It was real work to turn that car or truck. But now, with power steering, one finger can easily turn the wheel. That is a decent analogy to living life without the Spirit or being filled with Him. Life is simply easier lived in the power of the Spirit.
I use the acronym C DAT U (imagine a Chicago mobster saying to one of his cohorts, "See dat you?" :<) to help people remember how to be filled with the Spirit.
C-Confess. God won't fill a dirty vessel. Get cleansing for your sins so that God can fill you up.
D-Desire. He that hungers and thirsts after righteousness shall be filled.
A-Ask. If a wordly father is glad to give good gifts to his children, how much more shall your Heavenly Father give the Spirit to them that ask Him?
T-Thank. Thank God, as an acknowledgement, for the precious gift of the Holy Ghost. It is only decent to be grateful for such a wonderful gift.
U-Utilize. We are filled with the Spirit for many reasons, chiefly, to win others to Christ. Acts 1:8 "But ye shall receive power after that the Holy Ghost is come upon you, and ye shall be witnesses unto me..."
What I have just written you is life-changing. I beg of you, right now, bow your head and get filled with the Holy Ghost of God. You won't believe the difference. Or...continue swimming in peanut butter.