It's a bit confusing, but it works like this:
LOAD and SAVE in the Map tool save it in a format for editing in that tool, as a single MAP_NAME file.
SCSAVE saves it in a format easier for using in programs, by saving it as four files from SC_NAME_L0 to SC_NAME_L3.
These files can then be used with code like this:
DIM MAP[0]
FOR I=0 TO 3
LOAD "DAT:SC_NAME_L"+STR$(I),MAP,0
BGSCREEN I,64,64
BGLOAD I,MAP
NEXT
You'll notice a delay between each layer being loaded. This is because LOAD is somewhat slow. You can hide this delay by using VISIBLE to hide the BG while loading, or by LOADing all four layers into four arrays first before BGLOADing all of them.
