Save your own phone number as a contact in your phone
Open WhatsApp and start a new chat
Search for your own contact name or number
Open the chat and send yourself a message
If your own contact does not appear, use this link in your browser: https://wa.me/yourphonenumber
Replace yourphonenumber with your full number including country code, without spaces or symbols
Send a message to that link to open a chat with yourself
Use the chat to save notes, links, reminders, and files