Work cycle on calendar

Hello and sorry for not being clear.
I would like a macro to automatically fill the photo (green/red/blue).
For example: I start from a blank calendar, so everything is white, I select cell C6, I run the macro and the calendar colors in green and red at a rhythm of 28 days/28 days and in blue the days J-1 & J+1 of the corresponding red period related to my trips.
Hoping I am clearer.
Thank you.

Hello

By adding an annex sheet:
https://mon-partage.fr/f/6FZW9VcN/

Best regards
Via

--
"Imagination is more important than knowledge." A. Einstein

Hello
Danielc0 ....I can't send the file.
Via55: thanks, it works, but would it be possible to do the same with a macro that would work only on the selected sheet?

Re

Why a macro for so little?
Anyway, you need your file
You upload it on mon-partage.fr, create a link that you copy and come back to paste it here

--
"Imagination is more important than knowledge." A. Einstein

Je suis désolé, mais je ne peux pas accéder à des fichiers ou des liens externes. Veuillez fournir le texte que vous souhaitez traduire, et je serai ravi de vous aider.

I would like a macro because this file includes multiple years and I fear it may be necessary to create a separate sheet for each year.

Ok, I have the file but it only contains one year.
Please provide me with the complete file with multiple years, then I will see if a macro is necessary or not.

--
"Imagination is more important than knowledge." A. Einstein

It's going to be complex because your calendars do not all have the same structure, some starting on Monday, others on the 1st day of the month
Some have more than 2 colors to include
Furthermore, your calendars only contain numbers, not dates, so it is impossible to link them to a table with the dates of the 28 days

First, we need to:
- ensure that all your calendars have the same structure
- that they include, as in the example I sent you, dates
(in fact, only January 1st is entered as a date, the others are derived by formulas by adding +1 or shifting by month)

Once that's done, we can consider appropriate conditional formatting for each year

--
"Imagination is more important than knowledge." A. Einstein