Selfhosting is a huge topic, and can be very complicated, but it also doesn't have to be, once you learn some basics. A selfhosted application is an application that is designed to run as a website, and accessed as a website (this forum is such an application, XenForo ). Such an application is meant to run on a computer that's on 24/7, a server, and that is called hosting an application. Self-hosting just means running such an app yourself, on a computer you control.
So, how to host Homebox? The way I see it, you have few options here, in increasing order of complexity.
Pay somebody to host it for you - There are services, most notably PikaPods , that will run it for you. There's virtually nothing to do. The drawback is that it costs $2.7/month. You do start with $5 of free credit, so you can use it for a month and see if it is for you. You can also use it to inventory other things in your life, and Homebox supports multiple users, and multiple inventories, so you can split it with somebody and drive down the costs further. Homebox allows easy data export, so if you decide to switch later on when you know more, it is easy to export and setup again with all your data.
Run it on your own desktop computer - While the application is designed to run on a 24/7 server, you can force it to run on a normal desktop computer. If you go to its Github , and you download the file called homebox_Windows_x86_64.zip and unzip it, you can run it like any other Windows program. The app will be available via any browser using the URL http://localhost:7745 . This is easy free, but the drawback that you lose the instant accessibility; your desktop computer has to be on and running for the app to load on your mobile phone. You will also have an ugly URL, like http://192.168.1.10:7745 (or whatever your computer's IP is) if you want to access it from another device, and it will only work on your WiFi.
Rent a computer in the cloud to host it - Virtual Private Server, a VPS, is a virtual computer you rent from a cloud provider. It acts like a normal computer, and allows you to install and host things on it. However, only the computer is provided, you have to manage the installation and maintenance of Homebox yourself. At this point you have to learn basics of Linux, and basics of Docker. You still have to pay somebody monthly to run the computer for you.
Run it on your own server - A server doesn't have to be a powerful computer. It can be an old computer or a laptop, a tiny credit-card sized Raspberry Pi , Network Attached Storage device, even an old Android phone with some effort. In this case you have a decent amount to learn, but this is the ultimate freedom.
Few resources:
https://reddit.com/r/selfhosted is an excellent community.
A good intro video
This YouTuber does breakdown of applications.
If you're an organisation freak like me, selfhosting can be super interesting. There are other excellent and completely free apps that make imposing order on things much easier. You can manage your documents with PaperlessNGX or Papra , you can manage your cooking recipes with Tandoor , your can manage your plants with Hortusfox , your groceries and cooking supplies with Grocy , or shared household chores with HomeHub . You can find thousands more apps in this app directory .
Here's a roundup of other popular apps .
and I feel stupid because I don't know how to make my images come out not sideways 
