sorting - Microsoft Access Query to SUM & SORT in a query -

select ptmeds.station, ptmeds.txdate, ptmeds.patype, ptmeds.genmedname,  ptmeds.strength, ptmeds.unitsm, ptmeds.volume, ptmeds.dosage ptmeds (((ptmeds.station)="emer1") , ((ptmeds.patype)="withdrawn")) <i need @ genmedname field here also> group ptmeds.genmedname; 

i need able sum based on ptmeds.genmedname , sort results highest lowest. i've looked thru other responses similar question cannot find need do. appreciated.

select ptmeds.station, ptmeds.txdate, ptmeds.patype, ptmeds.genmedname,  ptmeds.strength, ptmeds.unitsm, ptmeds.volume, ptmeds.dosage ptmeds (((ptmeds.station)="emer1") , ((ptmeds.patype)="withdrawn"))  group ptmeds.genmedname order ptmeds.genmedname desc;