Welcome to the forums,
@ibanman555. No such thing as a silly question when you are getting started.
Your question, while it seems simple on the surface, is actually very complex and difficult to answer. Like many parts of this hobby, it really depends on how involved you want to get, and how willing you are to learn the many many many small details that make up the topic "motors and ESC combinations".
If you just want to get flying, and you want something that will absolutely, 100% work with the plane you are building, the FT power packs are a great place to start. Each plane has a recommended power pack that is compatible with that airframe, and you know that the guys at FT have put in the effort to make sure their planes fly the way they should with each one.
If you want to go for a deeper dive, I am willing to give you a general overview of the guidelines I use for powering my planes. These are by no means rules, as, if you forgive the expression, there are many ways to skin a cat.
----------------------
The first two factors to consider are the weight of the airplane and the desired performance level. There is a correlation between motor power, measured in watts, and airplane performance. This is called the "watts per pound rule" and as the title says, the performance depends on the AUW (all up weight) or weight including battery.
70-90 WPP is good for trainers and slow fliers
90-110 WPP is good for faster planes and scale fliers
110-130 WPP for racers and sport planes
130-150 WPP jets and most aerobatics
150-200+ WPP for unlimited vertical
These are just ballpark figures, but a good plance to start. Everyone will have their own preferences for powering aircraft. In general I like to "overpower" the majority of my planes and then just putz around at 1/4 to 1/2 throttle. Its nice to have some power in reserve if you need it.
Once you have the weight of your aircraft and you've decided on what kind of performance you'd like, its time to go shopping for motors. Shopping for motors is probably my single favorite part of this hobby, second only to trying out different motor/prop combinations. I'm a tinkerer by nature, and the experimentation has always been interesting to me.
Motors are measured and labeled differently according to their manufacturer, which is really obnoxious. A common format is XXYY-ZZZZkv, where
-XX is (usually) the diameter of the motor in millimeters
-YY is the (usually) length of the motor in millimeters
-ZZZZ is the kv rating of the motor, which is a measure of revolutions per volt applied.
I say usually because sometimes the stator is measured instead of the can.
Just based on these numbers, you should be able to work out that a 2215-2000kv motor is much smaller than an 3615-2000kv motor. In general, the larger the motor, the more power (watts) it puts out.
kv is a tricky number to wrap your head around. If you were holding two motors in your hand, for example a 2215-1000 and 2215-2000, they would be basically identical. Their performance, however, would be very different. In general, a lower kv motor will provide more torque, and be able to swing a larger diameter propeller. A higher kv motor will spin a smaller diameter propeller, but will do it much faster. Which motor you choose ultimately depends on the airframe its going in. Again, in general, I like high torque, low kv motors for my tractor-style aircraft, and usually run higher kv motors with smaller props on my flying wings.
Your watt output will also be determined in large part by your propeller. A large diameter, high pitch prop will load a motor much more than a small diameter, flat pitch prop. A must-have piece of equipment for anyone experimenting with motors and props is a watt meter. It is very easy to over-prop a motor and burn up your speed controller or motor when running it.
Best of luck, and I hope this helps a bit. Let me know if you have any more questions.
