Considering you have already upgraded your license I would reccomend you doing the following steps:
1- While on X, Install the demo you would like to start from.
2- Install PRO and activate it.
3- Validate your PRO Theme
4- If you don’t need a complex header, in order to avoid too much work as you might be overwhelm with the possibilites I would reccomend you sticking with the classic header and classic footer for now, and skip the PRO and Footer builder for later
5- Go to Pro > Theme Options > Explore all the tabs in order to set your general styling of your website, on Theme Options > header you can set your logo.
6- When you edit your pages, I would reccomend you starting with the classic elements, they offer fewer options but are still very powerful, and that should be enough for you to build your layouts. With time as you feel more comfortable you can explore the new V2 Elements and the Header and Footer Builder.
Hope it helps!