Fence tools you will need to build that much needed fence: First start with a Fencing Spade, Hole Auger or Post Hole Digger to dig a hole appropriate to the depth required. Hole Augers & Post Hole Diggers make lighter work of digging a hole but a fencing spade will help you make a nice tidy hole for a snug fit. Add gravel at the bottom of the hole to help drainage at the foot of the post. You can then consider using an Earth Rammer to help level & compact the base of the hole. If you want a nice shape to your posts use a Post Shaper which will let you choose a shape to suit.
Next use a Fence Maul or Post Rammer to push the post into the hole you've dug so that it's far enough into the ground to be stable & sturdy. Again use the Earth Rammer or a Fence Tamper to compact the ground around the post. For temporary fencing off, you may want to use Fencing Pins. If you are creating a wire fence then use Fencing Pliers to attach the wire to the posts.