I have a T4a I need to enter my prestation at box 107 where i can find this information and can I put all my past years contribution or only the contribution of this year

If you're using TurboTax CD/Download EasyStep Interview mode, you need to scroll down the page to see Box 107. Box 107 – Wage-loss replacement plan is on the left about 23 lines down.

If you are in Forms mode, on the T4A entry page there is a line that says “Click here to enter other boxes”. Click on the box in the column you are using and you’ll get a big list of other boxes. Box 107 – Wage-loss replacement plan is on the left about 9 lines down.

If you have T4As from previous years, you would need to add them to your tax return for those years. You can make changes after you have filed your tax return through the CRA or through ReFILE: https://turbotax.community.intuit.ca/replies/2647992