Cobalt ore has an orange color to it, as shown below. It is about as rare as gold ore, and occurs at around the same elevation of gold too (Elevation Y 30).
You simply just smelt the cobalt ore in a furnace to obtain the Cobalt Ingot, which is shown below.
You can also create Cobalt Blocks, which is the same way you would craft any other block.
Cobalt Tools have a durability of 593 and dig up blocks faster than iron, yet slower than diamond. Also, Cobalt Tools do not have very good enchantability. You would create them the same way you would create any other tool.
Cobalt Armor is in short, a very useful and efficient armor in Minecraft. Protecting more than Iron, however, less than diamond, the armor will do a good job at keeping you safe from the monsters of the night. Its durability also lasts somewhat longer than iron, making it an all around useful armor.
(FYI, each armor piece protects more than iron, so just don’t go wearing 2 of the pieces, it won’t help)