PayPal doesn't officially support sending funds from credit card to PayPal by default, but there is a way you can accomplish it.
Basically you need to purchase a dummy product from yourself. The easiest way to do this is by creating a custom payment link using PayPal's basic HTML variables.
Here's an example of such a link:
Replace the example email address in the link with an email address attached to your PayPal account.
Paste the link into your browser address bar to browse to it. You will be presented with a PayPal payment form that will show your name or business name at the top.
Enter a description and amount where indicated.
Depending on whether you were logged into PayPal or not, you will be presented with either the Guest Checkout page or a login page with a button "Pay with a credit or Visa Debit card" near the bottom. Do not login. If the button appears, click it to proceed to the payment details form.
On the Guest Checkout or payment details page, enter your credit card and address information.
Importantly, enter an alternative email address not connected to your PayPal account. If you use gmail or Outlook webmail you can simply use an email alias e.g. firstname.lastname@example.org will deliver email to email@example.com. If you use Yahoo you can create a disposable email address.
Note: You will be charged PayPal's standard merchant fees for the purchase, usually around 3%.
Click the "Pay Now" button to make the payment from your credit card.
You're done! The funds will appear in your PayPal account shortly.