How much of Coding Theory needs to be learnt for understanding Post-Quantum Algorithms (like McEliece etc) based on Codes?

I don't know Coding Theory at all - not even Hamming Codes.

I know pre-Quantum Asymmetric systems reasonably well & I also understand Abstract Algebra reasonably well.

I was trying to look up Coding Theory & it seems like a separate subject by itself. Is everything in the whole of Coding theory relevant for PQC Coding Systems?

Is understanding the basics enough - if yes, what would constitute basics in a typical book on Coding Theory (I need to look for the right book also).

**EDIT:** For e.g. to understand Pre-Quantum Elliptic Curve Cryptography, I don't need to know deep algebraic geometry - just the basics are enough - I don't need to know Affine Varieties, Isogenies, Riemann–Roch, Divisors, Weil Conjectures etc as long as I am not planning to design something new based on ECs. Just understanding basics of EC over Finite Fields, addition/doubling of points, additive group, algebraic closures etc is enough.

I am looking for something similar for coding theory - how much of coding theory do I need to know - how deep do I need to go?