Upper case letters are used at the beginning of a sentence.
There is an upper case letter at the beginning of this sentence.
This sentence also has an upper case letter at the beginning.
We always use an upper case letter with "I".
I am happy.
I am going to the beach.
We use upper case letters for names of people or places.
Peter please meet John.
I am going to Sydney for a holiday.
We use upper case letters for names of festivals, holidays, days of week and months of the year.
Next week is Christmas. Can you believe it?
Today is Thursday.