Disable past days and give days a colour in a Calendar

[Malor]

Hi Guys,

I'm trying to set up a signup form for our users to sign up for trainings.

I want to have Calendar that has disabled the past days from Today.
And I have an sheet with all the planned trainings by Date.

so For Example:

26-3-2018 Training Outlook
28-3-2018 Training Excel

So I want to highlight those days with different colours to let the user now that there are trainings on those days.
Should this be possible ?

Attached the wanted calandar.Microsoft Excel.png

[Malor]

any possible solutions??

[Malor]

Does someone have an idea ?

[Malor]

Or mabye some other solution to pick ?