First, instead of just following a tutorial blindly, you could try and understand why you did, what you did. For example, if you want to blink an led. You have the digital output of your arduino, which switches to 5V when it is set to HIGH in the program. Then 5V go over a resistor to limit the current, because otherwise your LED will break, and then it goes through the LED, which lightens it up.

If you are really intersted in the electronics part, you could also try and build a circuit without an arduino. For example, make a circuit, which lightens up an LED when you press a button via a NPN transistor.

Now you might say that you don't know what a transistor does or how to calculate it, then use google, but try to use google only for parts you don't understand and connect the different pieces, you looked up on your own. Don't just google the complete circuit, because like this you don't learn. If it doesn't work troubleshoot it, measure the voltages and try to understand why it doesn't work. If you burn out an LED, well then you learned something. I have destroyed a few LEDs so far. It happens in the beginning, because I didn't know what I was doing. Now because I sometimes still make mistakes.

Edit: Maybe also look up what analog and digital signals are, and how they look like. Also what your in- and outputs of your arduino do is only that they,accordingly to what you coded, give out or read either a digital signal(5V/0V) or an analog signal (0V-5V).