1998 Ford Explorer aweful noise coming from front end

Hey Guys! My name is Jerry Cisneros. I own a 98 Explorer XLT 4X4. My mileage is around 105,000. I am asking a question about possibe 4X4 problems. My girlfriend was driving my truck one day and when she returned she asked me, "why is the explorer making funny noises?". I thought she may have hit something, you know. Ha ha Anyhow, I got in, and when I took off, I was shocked at what I heard. It is almost like a hard grinding noise coming from the front differential, or at least it seems that was where it is coming from. Now, I had realized that I DID take off more agressive than usual, but not bad. So, I went to a nearby parking lot. I stuck her in 4WD and it started to grind very badly. Thing is, I have never had a 4WD before this one, much less work on one. I am not sure if this is something that can be fixed at home, or do you reccomend this gets the attetntion of a shop?