Maps - Azeroth - Eastern Kingdoms - Tirisfal Glades (1-30)
Scarlet Entrance map

For the Scarlet Monastery Entrance you need to go through one of the doorways on West end of the Monastery until your minimap changes from the terrain map to the interior Monastery map. Your minimap still won't say "Scarlet Monastery Entrance", but if you pull up your map it will show the interior map and at the top it says "Scarlet Monastery Entrance"

Despite the illustration the doors are on the North and South walls not the West end.