I would always want a flashgun that has tilt AND swivel in the head, as well as one that has manual as well as PTTL. Point and shoot flash is just too hard in most cases when all you want to do is just "lift" parts of the image. Personally, I'd spend the extra $10 and buy the 36AF-5. When you get into using flash and become more confident in it. having a more flexible flashgun is VERY useful. I tend to use flash on manual with wireless triggers for lots of stuff. If you can find one second-hand then a 48 AF1 or 48AF2 is also a good starting place as well. Is it a K3 or a K3 II? The K3 has a built-in pop-up flash gun which can be used to trigger other guns. The 48AF1 can act as a slave from memory (not done it for a long time and now use 58AF1s instead with cactus wireless triggers).
It comes down to what you want to do with it and how much you want to learn. Have a look on some of the strobist websites for guidance.
Strobist: Lighting 101 is a site I've found to be very useful in the past... There's lots of starter information and more advanced information on there as well.
Knowing how to use flash manually is the best way of learning as you then understand what is important in shooting flash and the different effects. It is about why you've got a K3 rather than a simple point-and-shoot.
As you admit you've got no experience of advanced protography, I'd suggest that you start shooting without flash first of all and get to grips with how aperture/ISO/shutter speed affect the image you are taking. With flash, it changes the dimensions of taking images quite a bit as the aperture tends to rule more than the other two.
Welcome to photography and the fun of making images!