You can receive Wollo from another person (or your own exchange wallet) by simply supplying the sender with your public key (think of your public key as your account number).
To access your public key visit the transfer section of the app using the two arrows in the bottom navigation bar.
Then select ‘Receive’ at the top of the screen
Within the "Receive" section you are shown a QR code (which contains your public key) and your public key.
If the person who is sending you Wollo is with you they can scan your QR code with their device to get your public key.
Or you can copy your public key to your clipboard and share with with the person sending you Wollo.
It is always advisable to ask the person sending you Wollo to send a small transfer first to make sure everything is working before any larger amounts are sent.