Shopify Developer for Template Website

I have a Shopify site with a premium template and I want someone to help me customizing some parts of it.

Template used: https://themes.shopify.com/themes/cascade/styles/classic/preview

Add lines underneath the navigation, remove arrows, add lines around some images, and some formatting things Like this:

https://flavedoandalbedo.com
https://articleoneeyewear.com/