Firstly,
Thanks for letting me join LinuxQuestions and I hope I get to really understand this great concept.
I am looking for help.

I love Xubuntu but I am a complete newbie to terminal commands and do not understand even the basics of this dark art.

My printer is a Ricoh sp112su and will not work in my current upgrade of Xubuntu 18.4 yet it works without problem in Windows. About a year ago before my upgrade it worked without issue on Xubuntu.

I have downloaded the ricoh-sp100-master.zip and extracted it revealing 7 files;
1. check-requirements
2. pstoricohddst-gdi
3. RICOH_Aficio_SP_100.ppd
4. RICOH_Aficio_SP_204.ppd
5. README.md
6. LICENSE
7. INSTALL

The install file states:

installation procedures:

1) Open terminal, execute `check-requirements` script, you should see, that
all required components are correctly installed and available.
How do I do this and what am I looking for?

2) Install unavailable components
How do I know what is unavailable; What do I install from where and how?

3) Copy `pstoricohddst-gdi` to cups' filters directory (usually
/usr/lib/cups/filter).
When I try to copy or move file from above to this directory the folder bounces back. Obviously it is not allowing me to do it. What am I doing wrong?

4) Make sure it is executable by lp user and owned by root:root (i.e.
chown root:root pstoricohddst-gdi)
I do not understand any of this - what do I make executable and how and where do I do it?

5) Add printer through CUPS' web interface (usually
http://localhost:631/), click 'Choose file' and select one of provided PPD-files
This part I have discovered already and it looks straight forward.

6) Print!

While it might be easier to get a newer printer I firmly believe in ‘waste not, want not’.

Anyone's help would be greatly appreciated.

You don't say where you downloaded this from, but there are most probably instructions on how to do this on the website..and also in that README.md file. To run this script, you type in "./check-requirements" from the directory where you unzipped things to.
Because the script will *TELL YOU* what's unavailable.
Since you don't say what error you're getting, or how you're trying to copy it, we have to guess. And it is most probably due to the fact you aren't running that command as sudo, so try "sudo cp <SOURCE> <DESTINATION>"
They gave you the command..you type in "chown ..." to make the file owned by root:root, as it says. Again, probably have to prepend sudo to it. Same with "sudo chmod 755 <FILENAME>" to make it executable.
No, it's not easier, since this is a VERY few simple steps. Look in the README file and look back on the website where you downloaded the file and read their instructions.

Thank you TB0ne for your reply

I was directed to github by reading the posts of ‘AwesomeMachine LQ Guru’ and ‘ferrari Senior Member Contributing Member’ and downloaded as suggested :-
wget https://github.com/madlynx/ricoh-sp1...ive/master.zip

The installation stated in those postings is the same as I relayed in my post and which was in the install files as the readme contained no install details.

1. I extracted above zip in downloads directory and have since opened terminal in the extracted folder and typed in terminal ‘./check-requirements’.
The terminal reads as ‘~/Downloads/ricoh-sp100-master$ ./check-requirements’ .
I hit enter and a new line appears ‘~/Downloads/ricoh-sp100-master$’.
There is no other detail so my question remains.

2. Obviously item 2 cannot be actioned as I have no details.

3. I thought this meant to copy the actual `pstoricohddst-gdi` file from downloads then open the file-system file folder from the desktop and paste it in the ‘cups /filter’ folder. This is what I tried to do but it would not paste into the folder. I did not try to run it in the terminal as it never mentioned it.
So should the terminal entry literally be written as "sudo cp <pstoricohddst-gdi> <usr/lib/cups/filter>". I presume I should enter this only after 1 &2 have been resolved.

4. I also presume I then type in the terminal, ‘chown root:root pstoricohddst-gdi’ or ‘sudo chown root:root pstoricohddst-gdi’ and hit enter. Do I need to also enter "sudo chmod 755 <FILENAME>" with pstoricohddst-gdi being the filename or is this just an example of a similar event?

5. I am able to follow.

6. Hopefully I will be able to print.

As you can see I need guidance (and to corrupt a famous quote) this problem is... ‘one small step for the knowledgable but one giant leap for the newbie’.

What question??? If it doesn't tell you that anything is missing, then **THERE IS NOTHING MISSING**. So...
...there is nothing to 'action', since you don't have to install anything further.
1 and 2 have ALREADY been 'resolved'. Step 3 needs to happen, and in order to copy files to system directories, you need root privileges, which is what sudo does. You don't put file names in the <> brackets, those were for illustration purposes only. There is a LOT of documentation on the copy (cp) command you can look up, with examples.
You again omit the brackets, and again run the commands with sudo.
Everyone is a newbie at some point, but there is so much information, examples, and documentation on how to copy a file, what sudo does, etc., that you should be able to answer most of your own questions. EVERY command in Linux has a manual, also known as a 'man page'. Typing in "man <COMMAND NAME>" pulls it up, such as "man cp"...gives you an entire explanation of the command, every flag/option it can take, and a good number of times examples on how to use that command.

WOW!!