I am stuck on 1st island

[kcwong]

You can also press "T".

Some elements of the UI are rather subtle... so in case you don't know (I didn't until level 40 in my first game)...
- You can sell spell scrolls you don't want to free up scroll inventory space and get some money back. Open your spellbook while you're in a castle.
- You can store unused troops inside castles. There are 3 empty slots on the left side, just under the troops for sale.