Clothing generally represents the roles that we play in life and how others perceive us.
If putting on pants or changing your pants, plays a major part in your dream you may be questioning your role at work, home, or in any other area of life. The physical look of the pants, who is wearing them, and the emotional content of the dream will give you clues to its meaning.
If your were trying to cover up your genitalia, then the dream may be bringing up sexual issues.