HELP with some basic (I think) electronics

You are correct. The Arduino I/O pins cannot output enought voltage and current to control a relay directly. It needs a relay driver circuit which consists of a transistor and some resistors. Since you are new to electronics, you can use something called that relay module which consists of this driver circuit built on the module itself. So you can simply power the module and control it with Arduino.

Now that you want to control the motor in CW and CCW direction you would be needing two relay module. Also note that it is not possible to control speed using relays,if you are onto speed control as well then you should use MOSFET in H-bridge configuration.

If you are not into speed control then you can use the relay in following method. As we know reversing the polarity of the motor terminals will change the direction of the motor. So we will need two relays like shown below to change the rotation direction of the motor 

Getting started with basic electronics is easier than you might think. This Instructable will hopefully demystify the basics of electronics so that anyone with an interest in building circuits can hit the ground running. This is a quick overview into practical electronics and it is not my goal to delve deeply into the science of electrical engineering. If you are interested in learning more about the science of basic electronics.

By the end of this Instructable, anyone with an interest to learn basic electronics should be able to read a schematic and build a circuit using standard electronic components.
There are two types of electrical signals , those being alternating current (AC), and direct current (DC).
With alternating current, the direction electricity flows throughout the circuit is constantly reversing. You may even say that it is alternating direction. The rate of reversal is measured in Hertz, which is the number of reversals per second. So, when they say that the US power supply is 60 Hz, what they mean is that it is reversing 120 times per second.
With Direct Current, electricity flows in one direction between power and ground. In this arrangement there is always a positive source of voltage and ground (0V) source of voltage.
Speaking of voltage, electricity is typically defined as having a voltage and a current rating. Voltage is obviously rated in Volts and current is rated in Amps.
Electricity can also be defined in terms of resistance and watts. We will talk a little bit about resistance in the next step, but I am not going to be going over Watts in depth. As you delve deeper into electronics you will encounter components with Watt ratings. It is important to never exceed the Wattage rating of a component, but fortunately that Wattage of your DC power supply can easily be calculated by multiplying the voltage and current of your power source.

The answer to your query, which you ask on this platform, is you can use any of the arduino development board, as all of the arduino boards provide output of 5V and some milli-amps of current. But for connecting loads with arduino I/O pins such that a 12V motor or pump, we need to use a relay or its development module with features of opto-isolation using PC817, available in market for arduino kits, you just need to power up the module, attach digital pin of arduino and connect 12V power supply with relays contacts and then your motor. Here I would like to suggest you to get connect with the techical support team for getting better assistance regarding your projects.

The answer to your query, which you ask on this platform, is you can use any of the arduino development boards, as all of the arduino boards provide output of 5V and some milli-amps of current. But for connecting loads with arduino I/O pins such that a 12V motor or pump, we need to use a relay or its development module with features of opto-isolation using PC817, available in market for arduino kits, you just need to power up the module, attach digital pin of arduino and connect 12V power supply with relays contacts and then your motor. Here I would like to suggest you to get connected with the technical support team Sierra Software Ltd. platform, for getting better assistance regarding your projects.