How can I modify the banner and collection images on the Dawn theme?

[CamiC]

Hi everyone, hopefully, someone will be able to help me. 

My url is https://simplycolors.cl/?key=8a1f8cd4e2899d7fa64d23826ce0b90124cc0e7e7205a139235fd2295763635d 

I´m using dawn theme and I need help with to things:

1. I want to add a slider on my banner image on my main page:

2. On my main page I have the collections, and I want to erase the arrow and the grey square around the image

Thanks!