OK, your attachment pic helps. It tells us you are totally in the wrong place.
I apologize if the instructions to copy your theme into the home folder confused you. It seems that is where you are trying to edit the theme, but you did not copy the theme there correctly. I'd say just delete the .cinnamon folder that is in your home folder for now.
And let's start again... (at least until Wizard gets a video of this process, but maybe that won't be necessary). The steps below should get you to make the clock changes to your current theme (the default Mint-Y-Dark).
1. Open Nemo, your file manager. Near the top, there is an "up arrow" (below the View menu). Click it until you cannot go up anymore. You should see many folders like bin, boot, etc, home, tmp, usr, var (and more probably). If you don't see these folders, stop and let's go over this again.
2. Scroll down to the
usr folder and double-click it to enter it.
3. Scroll down to the
share folder and double-click it to enter it.
4. Scroll down to the
themes folder and double-click it to enter it.
5. Scroll down to the
Mint-Y-Dark folder and double-click it to enter it. Don't mix this up with other Mint-Y folders. It must be
Mint-Y-Dark.
6. Now... right-click on the
cinnamon folder and choose Open as Root.
7. Double-click on the
cinnamon.css file to open it with the text editor.
8. Hit CTRL-F (opens a small Find search box) and type (without quotes) "
applet-label"
9. Below the font-weight line, add a new line and insert "
font-size: 18pt;" -- no quotes, but it does need the colon and semi-colon as shown, and as matches the other entries in this file. Don't capitalize anything.
10. Hit CTRL-S to save the file. Do not close it in case you want to adjust the size.
11. Hit CTRL-ALT-ESC to reload the desktop. If the screen goes black and doesn't restore, hit CTRL-ALT-ESC again and it should come back. (This seems to happen to me regularly.)
12. If the 18pt font is too big or too small, change it in the file, CTRL-S to save it again, and CTRL-ALT-ESC to reload the desktop.
Done!
Yes?