This'll be for me then

Two ways, both easy; this all assumes you have a relatively recent cycle, of course...
1. Just "cheat" (as it were) and use the DEP/ARR page to select the correct SID and/or STAR.
2. (And doing the above would show you this graphically), enter the SID as <identifier>.<exit_point> and use the appropriate LSK to enter it: BPK5K.BPK
I can heartily recommend Bill Bulfer's excellent FMC user guides - they're not particularly cheap (neither are they expensive though) but they'll teach you everything about the Boeing FMCs