First, the simplest case: you have a single byte in memory and you want to load it into a register:
: data 0xAB ... i := data # set i to the base address load v0 # load from i into v0
Slightly more complex: you have an array of up to 256 bytes, and you want to load one by index into a register:
: data 1 1 2 3 5 8 11 ... i := data # set i to the base address i += v1 # add an offset (in this case, the value in v1) load v0 # load data[v1] into v0
Same as before, but now we want 2 bytes:
i := data # set i to the base address i += v1 # add an offset. items are two bytes wide... i += v1 # (we alternatively could have pre-doubled v1.) load v1 # v0=data[2*v1], v1=data[(2*v1)+1]
Are those cases clear?