How to redirect Nginx port 80 to 8080 Tomcat and make webapp main page?

Hello,

I have site (its name is not real but something like) http://example.co
Tomcat it installed there on port 8080 with web app. http://example.co:8080/web_app/

The question is which Nginx server in nginx.conf configuration should i use to get web_app as http://example.co main page without port 8080 in URL and any external slashes?

I tried this manual:

https://stackoverflow.com/questions/19866203/nginx-configuration-to-pass-site-directly-to-tomcat-webapp-with-context

and also this

https://www.digitalocean.com/community/questions/how-to-change-the-default-nginx-page-to-my-web-application-home-page

but it does not work for me. It just redirects to 8080 port but i need to web_app page which should be opened as a main site page http://example.co without web_app suffix.