There is a great deal of diversity among the many, many different churches that place themselves under the name “Christian”. They differ in organizational structure, and important aspects of theology and in relationship to the world around them Despite all this diversity, the one great unifying factor of all of these “Christian” churches is acceptance of the importance and necessity of baptism. Catholics baptize. Lutherans baptize. Baptists baptize, etc., etc., etc.
Having said this, most of us are aware of the fact that although baptism is a great unifier, it is practiced in several different forms. Many of today’s fundamentalist churches practice by immersion- that is, the person being baptized is actually submerged briefly beneath the water, only to emerge quickly as a baptized Christian.
Some of the older churches such as the Roman Catholics, Lutherans and Episcopalians, use a simpler form, namely pouring blessed water over the head of the person being baptized, whether that person is an infant or an adult.
Those using immersion properly see baptism as symbolically entering into the death and resurrection of Jesus and this is wonderfully symbolized by the person being baptized going beneath the water (symbolizing death) only to rise from the water (symbolizing return to life). Personally, I think this is truly meaningful symbolism but it has some logistical problems connected with it. Rivers are not always convenient. The churches using flowing water over the head of the person hold that water is the essential matter and form of baptism, as long as it is poured with the one baptizing doing so in the name of the Father, the Son and the Holy Spirit. It is interesting that immersion has made a come back in many Catholic parishes.
Regardless, Catholic tradition accepts both forms, so the choice is yours!