Before you get to the circle of 5ths, what u should do is learn the chord patterns. Memorize this musical Zip Code: (7)-3-6-2-5-1-(4)
Once u know this pattern, you can use the circle of 5ths. As it regards to music, the circle of 5ths serves 2 purposes. Reading the circle clockwise, the notes are in 5ths. They represent how many sharps or flats are in a certain key.
C (0 sharps or flats)
G (1 sharp)
D (2 sharps)
A (3 sharps)
E (4 sharps)
B (5 sharps) / Cb (7 flats)
F# (6 sharps) / Gb (6 flats)
C# (7 sharps) / Db (5 flats)
Ab (4 flats)
Eb (3 flats)
Bb (2 flats)
F (1 flats)
Now, if u read the circle counter-clockwise, the notes are in 4ths. This is how your chords move, in 4ths. Remember that musical zip code I showed b4? Those numbers are in 4ths. Here's how the circle looks in reverse:
C
F
Bb
Eb
Ab
Db/C#
Gb/F#
Cb/B
E
A
D
G
So, let's utilize this knowledge with an example:
Let's start on the note C.
C
Now, let's say that C is 1. If C is 1, what is 4? Going from 1 to 4 is a movement of a 4th. So, to see what that note is, you would look on the circle of 5ths and find the note C. Next, would read the circle backwards 1 note to find the 4th movement. The note u land on is F.
Now, let's say u want to know what the 3 is. How do u find it? Well, what u have to do is read the circle in the other direction to get to 3.
So, u start with C being 1:
C (1)
Then, u read the note that came befor it, which is G. In the musical zip code, a 5 comes before 1. So, G must be the 5:
C (1)
G (5)
Then, u do the same process until u get to 3:
C (1)
G (5)
D (2)
A (6)
E (3)
You see how that worked? All of those notes are found on the circle of 5ths. It all depends on which direction u read it in.
Does that help any?
