If you are noobish, and if you are interested in connecting a Discourse Forum to your Ghost, you might find this resource helpful.
Previously I have installed a Discourse Forum on Digital Ocean, but spent a lot of hours flailing around. I just could not find a cogent tutorial, or get any help or support at Digital Ocean.
Recently I had a comparatively terrific experience on Linode starting with this tutorial on Youtube:
The pricing on Linode is $5/mo for the same (minimal) configuration I (finally) had running on Digital Ocean.