Instructions
Kill monsters. Each monster or enemy you vanquish may have some cold hard cash somewhere on their person. Loot their bodies once you have killed them, to collect any coins they may have.
Sell items. Almost everything in "Wizard101" has a price tag on it. You can sell old equipment or unused items for a tidy profit at one of the many shops.
Complete quests. Most quests in "Wizard101" will reward you monetarily when you complete them, with more difficult quests earning you more coins.