Reboot:
Following on from the above should be this screen.

Just click the Yes button.
On installing upates. You will not always be required to reboot. However many users will do this regardless. It ensures the Operating System has registered any changes in the program.(Recommended)
On rebooting with the initial installation or clean re-install. The following window should appear.

Just click the appropriate button.
Order if you want to purchase then.
or
Continue to take advantage of the trial period of 21 days.
Clicking on Continue should take you to this screen.

On reading the brief note (Important info), click the OK button.
Just to check the trial period at a later stage. (See how days left etc). Click on Information (can be seen in the above screen shot, bottom of menu on the left hand side).
This should give you the following screen.