To know which charities you contributed to in 2019, you need to have a receipt from the charity. Without a receipt from the charity you are not allowed to take a deduction on your tax return.
These receipts you need to have and keep with your tax records.
If you do not have enough Itemized Deductions, when added together are greater than the Standard Deduction for your filing status, you will just receive the Standard Deduction.
The Standard Deduction for 2019 is
Single $12,200
Head of Household $18,350
Married Filing Joint $24,400
Married Filing Separate $12,200
Itemized Deductions are Mortgage Interest Paid, Property Taxes Paid, State Income Taxes Paid, Medical Expenses that exceed 7.5% of all of your income and Charitable Contributions.