Attila.
At your stage in the theory course you have not yet encountered minor keys.
Here is a simple version.
You’re along with the right lines with key of C and a question mark over Fm.
Key of C
C, Dm, Em, F, G, Am, Bdim
The relative minor key is A minor.
Start at Am and use the exact same chords but reordered.
Am, Bdim, C, Dm, Em, F, G
You have hopefully encountered the idea of a 12-bar progression.
In the key of A that would be the chords A, D and E which are hte I, IV and V respectively.
In the key of A minor, the equivalent would be using the chords Am, Dm and Em.
I write those chords using lower case Roman numerals i, iv and v.
Red RIght Hand is a blues-based song in the key of A minor using the i, iv and v (1, 4 and 5) chords.
It also introduces an out-of-key chord. This is a borrowed chord. You can explore theory to explain and understand it. but you can also simply accept it is there because it sounds good. And it only happens for a brief moment to give an element of surprise.