The knit front back increase is one of the easiest increases; it's just as it sounds! You knit once into the front of a stitch, then without finishing, you go into the same stitch again (but in the back this time) and knit it a second time.
Knit front backs leave a little "purl" bump on the knitside of your work. These are less visible when working in garter stitch or reverse stockinette.
Knit front backs are similar to purl front backs, the only difference being that you purl instead of knit into the front and back of the same stitch.
If you haven't already, familiarize yourself with the different styles of knitting before continuing. There are three different ways to hold your yarn when knitting and you want to make sure you're watching the right technique for you.
kfb - knit front back