1) a server (basically any spare computer can be made into a server if really you can't buy new hardware)
2) a spare USB drive (for installing Debian)
3) a computer (for making the installation USB)
4) an internet connection for your server. I highly recommend ethernet. I will assume you are using ethernet.
Making the installation USB & Installation
1) Download your preferred Linux distro ISO. (I will be using Debian as an example. The latest Debian netinstall ISO as of 20 March 2020 is here: https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.3.0-amd64-netinst.iso
2) Download and run Rufus. ( https://rufus.ie/
) Make the bootable USB using your ISO file. Make sure to choose the correct USB device. I think this part should be easy without explanation. Rufus allows you to make bootable USBs using an ISO file. An ISO file is basically a single file that has the contents of a DVD/CD.
3) Plug the USB into your server. Please have a monitor connected for this part. Boot the server and repeated press the UEFI/BIOS/boot menu key. (Possible examples include: Esc, F12, F1, F2, etc..) Refer to your motherboard manufacturer. (For example, I have an Asus motherboard and my key is F2. Yours will probably be different. Google it and try different keys.)
4) Look for boot menu and select your USB. If you see this screen ( https://i.postimg.cc/Dz1RtBLX/debian-install-boot-screen.png
) you're ready to begin the installer. Choose the graphical installer. After answering the first few questions it will ask for a hostname and domain name. You can set the hostname to whatever you want. I set mine as "VM" because I'm running this in a virtual machine. You do not need a domain name and can leave it blank.
5) When you reach the "Partition disks" section of the installer you can choose "Guided - use entire disk" unless you have a reason to pick something else. Make sure you select the correct hard drive if you have multiple hard drives in your server. For the partition scheme pick all in one unless you need to use something else. Next, select "Finish partitioning and write changes to disk" and click on "Continue". Answer Yes for the next question.
6) When you reach the "Software selection" part of the installer. Please uncheck print server. You do not need that. Leave standard system utilities checked. Pick your desktop environment. I'm going to use LXQt. You are free to pick whichever one you want. If you don't know which one to pick, choose LXQt or search for each of them on YouTube.
I will add a post installation outline/tutorial later.