Load your program, then enter the monitor and use the "sl" command to
load your label file like this:
sl hello.sym
After loading the labels, they are used by Oricutron in the disassembler listing, and you may use them whereever you need to specify an address. Try
d ._main
as an example (note that VICE needs a leading dot before all labels, and that the compiler prepends an underline under most named labels).