Sounds like a generic thiourea toner. One bottle is the bleach; it's a generic ferricyanide/bromide bleach which will have a strong yellow color.
The other two are the thiourea and the activator, respectively. They should both be colorless. One of them will have a very high pH (it's either a carbonate or a hydroxide solution; usually the latter), the other will be rather hard to identify since a weak thiourea solution doesn't have very easily observable properties AFAIK.
For guidelines on use, refer to any of the documents on thiourea ('odorless') sepia toners. The ratios/concentrations will likely vary across manufacturers, but the basic principles are always the same.