Baptism is a public act of identification with Jesus Christ. It's a physical act of being immersed in water which represents His death, burial and resurrection.
It's an announcement to the world of your new life in Him.
Why don't you watch this video by Pastor Matt which explains baptism in more detail.
New Life Christian Church, 134 Main Road (Entrance via Thorney Road) Emsworth, Hants, PO10 8BN