This is for users on Shopify using the theme 2.0 option for their site. to add a slider widget, please follow the steps below
Go to Online Store in your dashboard
Click on Customize
On the top of the page, select where you want to add your slider widget.
I want to add mine on the homepage, above the footer section. So, I choose the add section option
Choose the slider widget
This is what it'll look like
Aways remember to save your work!