Confirm everything looks good, if there is any issues go back to the page you need by clicking the text under the circle-ticks in the top right.
Click the checkbox at the bottom and then click "Add to Cart".
Confirm all the details of the order are correct and then click "Go to Checkout".
If you don't change anything on this screen and you haven't selected the tuck-box option you will get an annoying pop-up, dismiss it and continue on.
Fill in the billing information.
When filling in the shipping information go from the bottom upwards, that is, start with Email and continue upwards, completing Country/Region last. Doing it this way will avoid the site needing to re-calculate shipping every time you fill in a field.
Look over the details one last time. Select PayPal (don't enter your Credit Card information on a Chinese site) and click Submit Order.