Dung Beetles are a very useful creature in Ark Survival Evolved. They make fertilizer and oil for very little work, plus they look cool while doing it. The Dung Beetles are a passive tame. Put poop in your far right slot on your hot bar and walk up to them to feed. Give them a taste and reload your hot bar with dung. There is no need to tame a high level one, it will mostly just make the process longer than it needs to be. I usually wear a ghillie suit and use some bug repellent to make it less likely that I will aggro the other creatures that are around. The Dung Beetles themselves don't aggro very easily.
Once the dung beetles are tame you will have to have a place for them to wander. Only when the dung beetles have been enabled to wander, do they produce fertilizer and oil. After you enable wandering you will need to put poop in their inventory, and that's it. I put all the dung beetles experience points into weight, so I can load them up with more poop, and tend to them less frequently. Now you will have fertilizer to place in crop plots. Dung beetles eat spoiled meat once they are tame, so make sure to have some in the feeding trough.
Adding fertilizer to crop plots, and placing them in a greenhouse will make gardening easier and the greenhouse effect will increase crop yields. A greenhouse is also a good place to have the dung beetles on wander.