Your homepage can be customised in a couple of different ways. To do this go to Settings > Store Settings > Homepage.
Firstly, you are able to set whether you would like to show all of your active categories on the homepage. This is done by clicking the dropdown and selecting 'All Categories'. After doing this, you are able to change the order by scrolling down and dragging and dropping the categories in to the order you would like to see them.
To show only the products, select 'all products' from the dropdown. This list can also be changed by dragging and dropping to show the order you would like.
To have a custom homepage where you can show a mix of products and categories, select custom from the dropdown.
If you scroll down to the view of the homepage, you are able to click on the '+' box to add a new product or category to the homepage and move it to the order you would like.
After you have the homepage you desire, press save and your homepage will update immediately.