A Registered Retirement Savings Plan (RRSP) allows you to save money today, and you don't have to pay taxes until you withdraw the money at a later time. You would have to contribute the money to a special account with a financial institution. In some cases, your employer may match your contributions, in which case it would be included on your T4 or T4a slip. Your financial institution will send you a receipt. You may also be able to find your contributions on the MyCRA portal if you have an account. Odds are, you would be aware if you contributed to a RRSP. The max you can contribute is 18% of your income, up to 26,500$.
A Registered Pension Plan (RPP) is an arrangement made by your employer or union to make periodic payments to employees when they have retired. Similarly, this would be included in your T4 or T4a.