How can I create miniature images for my products on Shopify?

Store Design
1

Hello All,

I am new to Shopify and trying to convert my webshop to Shopify.

I wanted to upload my product pictures but they are so big, how do i get miniatures in stead off the full pictures?

The link to my shop is:

https://744b2a-2.myshopify.com/

Thanks in advance!