When you install WooCommerce, it should add its standard pages – Cart, Checkout and My Account.
See Step 3 of the Shoptimizer install guide.
If you skipped that step, it’s no problem. You can still add them later. See our detailed WooCommerce install guide – under ‘Pages’.
WooCommerce > Status – click on the Tools tab at the top and scroll down. You’ll see a button to add any missing pages there.