Holiday Tracker

Guys

Thanks for reading my thread,,,
I have this problem , which i coulndt fix it past 3 days.

Basically what i need ,i want to select the name and mark the day and date with colour, i am able to do in until day 21 but after i cant mark and book the holiday....i also have problem to fix this date on columns, which they are not in order....

also, when i mark the date for someone on the list, that should deduct it from total holiday entitlements

Hope you guys understood what i mean

i attached the file, could you please have a look on this and repair it for me?

Thanks
Ben