Almost every week, I receive at least one letter from someone who's been trapped by pornography over the Internet. The Internet can be used for great good -- but it also can be used for great evil, and the widespread availability of pornography over the Internet may be its greatest evil.
The first step is to realize that this is sin in God's eyes. It isn't just a bad habit, nor is it only something that appeals to your lusts or your craving for excitement. It is sin -- and you must not excuse it or deny it or say that it doesn't really matter. It is sin -- and the Bible warns that "after desire has conceived, it gives birth to sin; and sin, when it is full-grown, gives birth to death" (James 1:15).
This is why I urge you to turn to Jesus Christ and open your heart and life to Him. He doesn't love your sin -- but He does love you, and He wants to come into your life and take away your sins and begin to change you from within. Commit your life to Him, and then ask Him to fill you and replace everything that is evil or wrong with His goodness and purity.
Then take practical steps to fight this habit. Get a program for your computer that will filter out unwanted sites -- and use it. Move your computer into a place where others can see what you are doing. In addition, share your problem with a trusted friend who can hold you accountable for what you watch.