There’s a caveat that you have to start on an older version of Nodebb, but:
Edit: looks like it was updated to support a more recent version of NBB 🎉
Hope to get vps from OVH which is cheaper than digital ocean. I'm not familiar with vps. If better someone guide me to get started
Check NodeBB docs for guides:
You want to run your own VPS which is similar to a dedicated server. I mean you have to choose an operating system (Ubuntu 14.04/15.04, Debian 7/8 or CentOS 6/7). Advanced Linux users can go with Arch Linux.
Do you have any experience in running a server?
I've successfully installed it on my local machine which is running by debian distribution. Bit familiar with git and terminal. Is that enough?
OVH offers pre-installed Docker which is one more alternative.
Yes, it's not so hard. Just make sure you know what you're doing. Go with Debian or Ubuntu (based on Debian) and start with hardening and updating a server (operating system).
When you'll have a machine running up-to-date software you can start installing Node.js, Redis/MongoDB and NodeBB.
Its worth mentioning that NodeBB runs perfectly without Docker. And if I remember correctly it preforms in a more unknown way.