Docker nginx multiple sites

Hello friends, i trying to use multiple sites, i got this, but i want to hide a port 4000 of my application.
I have 2 sub domains, demo.example.com and tst.example.com and i want connect demo.example.com/api and get the xxx.xxx.xxx:4000/graphql
how i do this?

my file docker
docker-compose.yml:
tst:
build: tst
environment:
VIRTUAL_HOST: tst.example.com
restart: always
volumes:
- ./tst

demo:
build: demo
environment:
VIRTUAL_HOST: demo.example.com
restart: always
volumes:
- ./demo

nginx-proxy:
image: jwilder/nginx-proxy
ports:
- "80:80"
- "443:443"
volumes:
- /var/run/docker.sock:/tmp/docker.sock:ro

restart: always
privileged: true