No you should have done this and been forgiven when you came to Christ and were born again. Now forget (go and sin no more) . Because God says once He has forgiven you you are white as snow and He has thrown your sins into the sea of forgetfulness to be remembered no more. You are a new creation in Him.
If you become a part of a church that does not have anything to do with being born again, which is the beginning of being a Christ follower. In fact in the majority of churches you be joining the churches of men and churchianity. And be brought into bondage to their system instead of being free to follow Christ. Remember Jesus died to deliver us from bondage. Being saved is a misnomer because the scripture say to be saved you must endure to the end (of either your life or the world). Going to a church does not equate to be ing a Christian. To become a Christian you need to admit and confess you are a sinner against God, ask His forgiveness, accept the bkood of jesus as payment for your sins, then change into the new creation you have become and follow Christ, not man.
The silly little prayer required by so many churches is a bad joke and has nothing to do with being born again according to scripture. You must also understand that what the church sysrtem calls chuch is not what the bible says. Inthe new testament god no longer lives in or recognizes a building, HE LIVES IN HIS PEOPLE AND WORKS THROUGH THEM.