"Ok Im going to star by saying hello and i'm new to cf and i wanted some advice because for a few things. First off im happily engaged to a wonderful woman. We do live together and we have two beautiful little girls."
IF you have two girls, and they're yours and hers then you ARE "Married" in the sight of God through the joining of flesh, but don't have the government's official approval of it yet (I don't know what the "Common law" ordinances in SC are).
Formalizing the Marriage would be a really good thing to do (for many reasons). While the more "Legalistic Churches would call it "Living in Sin" - it really isn't as long as y'all are committed one to the other, and live monogamously as a couple.
"i havnt the slightest clue on how to get married the right way and to not be living in sin anymore".
Simple - head on down to the city hall, and get a marriage license, and have the marriage legally formalized by either a minister or a Justice of the peace.
"and also neither of us has ever been babtised (sorry is i spelled it wrong) and i know we have to be to enter the kingdom of heaven."
This is the MORE IMPORTANT issue involved here. Chances are you're NOT "Christians" yet.
"Baptism" doesn't have anything to do with being "Born Again" - Becoming a Christian. That's accomplished By FAITH in the Sacrifice of Jesus for your sin.
You'll need to get with a Minister in a evangelical church in your area - Assembly of God, Church of God, Baptist, etc. And tell him you're concerned about your Relationship with God. They'll know what to do. And When you've become Christians, THEN you can be baptized.
And when you become Christians - then the Minister who led you to the Lord will be happy to marry you in his church, and celebrate your marriage with you. -
Simple as that.