Wanting to know about Mormonism is fine. Speaking to Mormon missionaries, who will no doubt be pushy about converting you, is not the best way to do it. There are online Resources by Catholic and other Christian sources. Mormons claim to be Christians and honestly believe they are, but they are not.
They reject the Trinity as all true Christians understand it.
- They believe that all three persons of the Trinity are separate Gods.
They believe Jesus was created by the Father as a spirit brother of lucifer.
- They believe that God the Father lives on a planet near Star Base Kolob, and
- have many other very unorthodox, heretical beliefs.
They are, as a rule, wonderful people with a great family ethic, love of neighbor, etc, etc. but unlike Protestant Christians, they aren't really Christian.
You can't be a Christian and believe Jesus was created. Jesus pre-existed eternally with the Father and the Holy Spirit, One God in Three Persons of the Same Substance, but as distinct Persons . . . . not three separate gods.
Unless you are very, very well-versed in the Scriptures and Catholic doctrine, I would advise not speaking with a Mormon missionary who is trained in proof-texting certain, selected verses out of context to persuade non-Mormons, especially Catholics, too many of whom sadly don't know their Bible, to convert to Mormonism.
He may tell you he's just there to explain and answer your questions, but he is trained to convert and his goal will be to convert.
I hope this helps,