After logging into your WordPress Dashboard, go to your left sidebar, select Slides -> Add New and add your content.
In your right sidebar, add a slide image by clicking on the Set featured image button and following the steps –
You should now see your chosen image –
Hit the Publish or Update button top right and you’re all set!
Next step is adding the slide to the slider. Go to your homepage and find the Slider block. Select it (click on it) to reveal its options and add the slide ID to the comma separated list, in the Slide ID(s) field.
Go to your Slides section in the WordPress Dashboard and check the 5th column. Use that ID for your Slider block.