Mysterious Song
Reaching Fawna

On the world map you can traverse through grasslands (light green) and forests (darker green). You cannot walk through boulders (grey) or water (blue).
Anywhere outside a town, monsters will randomly attack you. You should take every opportunity to level up as much as you can and even get some gold and minor loot. In fact, you may even want to grind for a bit because later enemies are extremely tough. The game's manual suggests grinding to level 50 but even that may not be enough unless you get extremely lucky rolls—and that is unlikely.
Travel east from the castle and cross a bridge (brown) to reach Fawna (2).
Recruiting Tiger
In towns you cannot walk through trees (dark green) and water (blue). You can walk along roads (light brown), across bridges (dark brown) and into buildings (white).
Once in Fawna, make your way to the south-east and speak to Tiger (marked 1 on the map). He is a fighter who will join you and will be a couple of levels higher than your current level. Whether you visit the shop or inn is up to you. Leave Fawna via the exit to the west when you're ready.