On Caladan we had air power and sea power, but on Arrakis we need desert power. To increase your Desert Power, first construct a Fremen Barracks, under the Buildings -> Military tab.

He who controls the victory points controls the universe.

To harvest the spice melange, we will need Spice Harvester Tokens. You may buy SHT in packs of 10 for $9.99, 20 for $18.99, or the best value pack of 50 SHT for $39.99