You can find the option to tip another user in your Wallet:
Click on the "Wallet" button
Go to "Tip" tab
If you are on the on-site chat, and you wish to tip specific user directly, you can also simply click on the selected username and choose "Tip".
Once in the Tip tab, choose the Balance you wish to send the tip from
Enter the exact username of the person you wish to tip
Enter the amount in the displayed currency you are using
Confirm by clicking "Tip user" button.
Please note that tipping another user is a non-reversible action, so kindly make sure you entered all the information correctly before you proceed.