I have set up Ubuntu Server 16.04 on my home network and want to access it from my browser at... school, for example. I asked a question about port forwarding to my Ubuntu Server on Ask Ubuntu and it was VedTC as off-topic and, after someone explained it, it made sense. However, I still have the question, I just don't know where to post it.
Unless there is reason to believe you will have to configure your Ubuntu server specially, my guess is that Super User would be the best Stack Exchange site for your question. I don't think I've seen your question, though. If you include a link to the closed question then more detailed advice should be possible. (Even if the question is deleted, 10k users will be able to examine it.)
If you're operating your server on a LAN where it accesses the Internet through a NAT router--if you're using a router marketed for home and small office use then this is almost certainly the case--then port forwarding will consist of configuring the NAT router to forward the port. This doesn't usually require you to reconfigure the server itself. Most NAT routers have a web-based setup page that you can use to forward ports, and which is accessed the same from any computer with a web browser.
Sometimes you want the port number that people use to access your server over the Internet to be different from the port number the server listens on and that you would use to access it on a LAN. (This is useful if the port is already in use, blocked, or otherwise inaccessible.) That's something you would do in your router's configuration, too.
If your question boils down to "How do I figure out how to forward a port, in general?" or "How do I forward port N on a model-X home router?" then it is probably off-topic for Ask Ubuntu but on-topic for Super User. Such questions have often already been answered on Super User (see below). If not, and you post a new one, you should of course post a detailed explanation of what you are doing.
For questions about how to forward a port with a specific router, you should give the make and model of the router, and either (a) show its setup page where you've looked for port forwarding but not found it or where you need help figuring out how to use it, or (b) explain how you have not succeeded at bringing up the router's setup page, if that is the case.
If you are in a special situation where the services must be configured to know the Internet-facing IP address through which they are accessed, and your question is about that, then it would probably be on-topic here (provided you're running them on Ubuntu).
Super User has a number of port forwarding questions that have been well-received, such as:
- What is port forwarding and what is it used for?
(written to address a recognized need for basic information on port forwarding)
- How does port-forwarding help in torrents?
- Are there good alternative HTTP ports rather than port 80?
- Allowing a friend to connect over the internet to a Minecraft server I've hosted?