You must enter your federal T-slip first under Income --> T-Slips --> check all the T-Slips that apply to your situation --> click Continue --> click Enter T-Slip if you did not enter the slip yet or click Edit on the right side of the slip (make sure you selected Qc as Province of employment) --> after entering the federal slip information go to the bottom of the page and click Enter Relevé 1 and you will be able to enter the information from your Relevé 1.  

Note that if you are not a Québec resident you need to make sure you check the Relevé 1 slip in the T-Slip list and a Box E (identify Relevé 1) will be added right at the bottom of the federal T-Slip page.