Not able to upgrade after creating stack

Hi, I am new to Rancher, Docker and GitLab CI. I’ve written a code to create stacks and its creating in Rancher. But I am unable to update the same. Could anyone please help.

stage: deploy
image: tagip/rancher-cli:latest 
   - rancher stacks create <stack-name> -f docker/docker-compose.yml -r docker/rancher-compose.yml --start

How do I upgrade the stack created?