Follow below steps to get everything done.
Click on Products from menu and click on +
Click on above link to get started. I assume you have added all your products before you click on above link.
Click on + to start adding categories
Provide your category information. Example of category name is Women Dresses, Health & Beauty e.t.c
Click on green plus sign to add products to the category created.
You can select multiple products to add to the category.
Click on gear icon above to configure how you want homepage to display your category.