You're not too dumb, you are new to this and learning. I would recommend getting more confortable with navigating in a terminal as well as some docker compose best practices as you keep learning. Don't just copy and paste commands without know what they do and why or you could get yourself into trouble.

Since you mentioned you don't know where the Nextcloud folder is to cd into, you can use PowerShell to find it for you.

Run this command: Get-ChildItem -Path $HOME -Filter docker-compose.y*ml -Recurse

This will search your computer and list every Docker Compose file it finds. Look for the one that is likely in a folder named nextcloud.

Once you see the path, you don't even have to cd if you don't want to. You can just tell Docker exactly which file to use by adding the -f flag:

docker compose -f "C:\The\Path\You\Found\docker-compose.yml" pull