Your credit use (or credit utilization) is how much of your available credit you’re using on each of your credit cards, as a percentage.
For example, if you have 1 credit card and it’s got a $1,000 limit and $100 balance, your credit utilization will be 10%.
If you keep your credit use low (it's suggested under 30% in Canada), spread it evenly across all your cards, and pay on time your credit score should improve over time.