Holes are going to happen the first few times! It could be several things happening, most likely dropped stitches, or what is called a yarn over.
Both can be fixed, and both can be used as design elements!
First off, dropped stitches happen to even the most seasoned knitter, and are just what they sound like. You dropped the stitch off the needle. Either it didn't quite make it all the way over to the right needle, or it popped off the right needle after you got it there. There are several threads here on how to fix those after the fact, and I believe there is a video here too.
Yarn Overs happen when you have the position of the yarn backwards from the kind of stitch you are doing. For a knit stitch your strand of yarn should be out the back and you are inserting your right needle into the front of the loop of the first stitch on the left needle. A yarn over happens when the strand of yarn is in the front of your needles, but you still do a knit stitch (into the front of the loop on the left needle). It leaves a little hole, and also makes an extra "stitch".
Again, it can be fixed, but I've not gotten that one down yet, so search around for threads on how to fix boo-boo's and you should find a fix.