There are three stages to becoming a full member of the local church community and the first most important one is baptism. The tradition in the UK is to baptise infants but it's not uncommon these days to baptise people at a later stage in their lives. In fact, it was the tradition of the early church that you where required to be an adult with a certain level of understanding of the faith before you could be admitted into the church through baptism.
Once an adult or young person is baptised and have under gone a short course of study and preparation they are introduced to the local bishop at a special service and are confirmed through the laying on of hands and the gift of anointing. This is a special moment for an adult on his or her Christian journey and is done in the midst of the local Christian Community known as a parish. Parishioners will pray for that person and often will offer support in a variety of ways, especially through friendship.
Having been both baptised by the parish priest and confirmed by the local bishop, the adult is then admitted to the Eucharistic celebration through holy communion. It is at this moment when the adult Christian becomes a full member of the local Christian community (known as a parish) and is able to grow in their Christian witness and identity through loving service. How the adult Christian serves the local community through loving service is for the individual adult Christian to discern and work out. The Clergy and others can often guide and suggest ideas, especially through what they preach on a Sunday and through prayer.
If this interests you please consider contacting your clergy person or approaching someone whom you trust and is an active member of their local church. They will be able to guide you through the initial stages of the process. Also have a look at the pages on this Website about Christianity, prayer and healing to understand more of what it is to be a Christian.