Hate to say it, but this is covered clearly by the base rules, page 9:
Step 1: Declare Attack
Step 2: Confirm Line of Sight
Step 3: Count Range and Roll Attack
Step 4: Spend Power Surges, Power Enhancements, and Fatigue
Step 5: Determine Attack Success
Step 6: Inflict Wounds
Spending surges comes after rolling the dice.