Please note that achievements in this game maybe a bit glitchy, but at some point, you will get it.*
The hoe is a tool used for farming. It helps make the dirt able to plant seeds to make food, just like in real life.
To make a hoe, you will at least need two sticks and two of any kind of material, such as wood, stone, iron, diamond, or gold. (I'd recommend wood or stone.)
Since this is PC, you'll be using the original interface, so to create one, it'll be created in of course, the 3x3 crafting menu.
Here is a link for everything you'll need to know about farming in minecraft as well. This includes how to make a hoe as well. Hope everything works out well ^^'
http://www.minecraft101.net/g/farming-plants.html