In The Forest South of Ellinia, take4↖Left side · upper level(you arrive on the left side, upper level)or5←Left side · middle level(you arrive on the right side, lower level)
There, take portal4↖Left side · upper level(you arrive on the left side, upper level, next to 1 here)or5←Left side · middle level(you arrive on the right side, lower level, next to 2 here)
Grey numbers are portals on another map: each opens that map with the portal picked out. A coloured number followed by "here" is a portal on the map above. Positions are from the game files, not tested in Classic World.
In The Hill East of Henesys, take2↘Right side · lower level
In The Forest South of Ellinia, take4↖Left side · upper level(you arrive on the left side, upper level)or5←Left side · middle level(you arrive on the right side, lower level)
In Swampy Land in a Deep Forest, take1↖Left side · upper level
In The Forest South of Ellinia, take4↖Left side · upper level(you arrive on the left side, upper level)or5←Left side · middle level(you arrive on the right side, lower level)