Write your own simple virtual machine[1] and a tiny assembler which accepts symbolic names for jump targets (e.g. goto LABEL). You'll need a link phase to resolve the symbolic names, and all will become clear. A few hours of time and anything involving linking, addressing[2], and so much more will instantly become intuitive to you.

[1] Array of opcodes indexed with a program counter (pc) with a giant switch statement for executing each opcode. A simple stack for data implemented as an array and a stack pointer/index (sp). There are plenty of examples online, just make sure you actually implement things yourself, and only go to the examples to answer questions you arrive at yourself. If you understand loops and arrays implementing the VM is trivial. If you can parse a text file line-by-line and split words, implementing the assembler is trivial. Working out the linking might take some thinking, but that's the point. It's like one night of work, max, unless you really get sucked in ;)

[2] E.g. Harvard architecture vs. von Neumann architecture