Firstly, a warm welcome to the forum, Lala21.
I hope you'll stay here and learn lots, and enjoy being here.
Firstly, we seem to have gone off track a bit, from the learning of the fundamental beliefs about Islam, so will address a point and then your actual question.
The sister has made it clear that she's a non-Muslim, she doesn't understand Arabic, so there is no point in using Arabic terms such mahram (a man who one cannot legally marry, such as brother, father, son etc), non-mahram (a man who one can legally marry, eg most men, and cousins and distant relations), which she doesn't understand. If you are going to use terms such as these, then define/translate them, so that their meaning can be understood by people seeking knowledge of our faith.
Lala21, in Islam, we have guidelines on how we interact with the opposite gender. A Muslim man or woman is not allowed to be alone in the company of a member of the opposite gender. Both men and women should lower their gazes, and behave in an appropriate manner in necessary interactions with the opposite gender (all this applies to non-mahrams only as loosely above), and indeed, if he is serious about you, he should introduce you to his family, with a view to marriage. Boyfriend/girlfriend type relationships aren't allowed in Islam.
This is not very different from the pure character of Mary, the mother of Jesus (peace be upon them both):
And mention, [O Muhammad], in the Book, [the story of] Mary, when she withdrew from her family to a place toward the east.
And she took, in seclusion from them, a screen. Then We sent to her Our Angel, and he represented himself to her as a well-proportioned man.
She said, "Indeed, I seek refuge in the Most Merciful from you, [so leave me], if you should be fearing of Allah." (Qur'an 19:16-18)
You will also notice that Muslim women who wear hijab (cover themselves), match more closely depictions of Mary (even though we do believe such depictions are wrong). You never see pictures of Mary (peace be on her) with uncovered hair.
As Muslims, we feel very close to Mary and Jesus (peace on them both), and you will find former Christians (including Catholics) who are now Muslim, say they feel closer to Mary and Jesus (peace be on them both) than they did when they were Christian.
The point here, though, is that you have asked for our help to learn about Islam, so that you can see what it entails, what are the beliefs, and practices, etc. Remember though, that if you accept Islam, which would be wonderful news, you need to be doing this because you truly believe in your heart Islam to be the truth.
Others have given some info above - I just want to add a couple of links on salvation and sin, which seems to be a sticking point sometimes among Christians interested in Islam.
http://www.islamicboard.com/discover...ation-sin.html
http://www.islamicboard.com/discover...ml#post1587820
Please do continue to visit the forum and ask any questions you may have, and we will do our best to help.
May Allah make easy for you the path to the truth, ameen.
Peace.