When you enter your T4 TurboTax will automatically transfer some information on your Relevé 1 if you entered Québec as your residence. You will access your RL1 from the bottom of your T4 page and enter your employee-paid premiums for private health services plans in Box 235. If your employer also paid a part of your premium you will enter the amount he paid in Box J (which could be the same amount but this amount is deductible only in Québec).
Please note that you will not see these amounts in your medical expense receipts but they will be included in your total medical expenses used to calculate the credit. Line 330 of Schedule 1 (CRA) & line 36 of Schedule B (Québec).