Creatine is one of the most researched supplement out there. It's classified as a type A which means it repeatedly showed an improvement and thus works. Furthermore no negative effects have been found in healthy individuals, so it's pretty safe.
There's tons of ways out there to take it but basically you need to build it up. Most cycles last 12 weeks with 1 week off, it's a substance your body makes so it's important to have an off week. Loading phases have NOT been found to be beneficial and are basically a marketing scam to increase your use. As to how much to take ... 5g./day for 12 weeks. I always take it in the morning, can't be bothered with taking it after a workout. You do need to drink plenty of fluids but you should always do that. Also worth mentioning that no other form of creatine has been found to give better results, lately you have creatine + insert something here that usually cost more but doesn't work better than simple monohydrate. You don't get an energy boost from it so it's not a pre-workout supplement and it does little to nothing to help endurance performance.
What does it do? It increases your ATP stores, when you workout ATP (energy) is converted to ADP. ATP (T = tri or three) loses a phosphate (the P) and becomes ADP (D = di or two). Creatine "gives" it's phosphate to the ADP and ADP + 1 phosphate = ATP again. Long story short ATP useful, ADP useless. In practice this should allow you to squeeze out an extra rep or two. Increasing the total volume or maybe a slightly higher intensity of the workout will be beneficial to overall gains.
Another fairly recent study showed the interaction between different supplements and creatine works well with beta alanine (also a type A supplement).
As to if you should use it? As mentioned it does work but don't expect a sudden vast increase in strength or muscle size. I use it because i've been working out for so long it takes a long time to increase my lifts and every bit helps. But macro and micro nutrients take priority to supplements when it comes to the importance of a proper sports diet. It's an extra and it depends on how serious you are about results. If you want to fully optimize everything and your macro nutrients, micro nutrients, rest is already optimized you could take it for a bit of extra gains.