Please do these steps
1. Go to your FTP, and go to folder "wp-content/plugins"
2. Create a PHP file there and name it with "bp-custom.php". But if you already have it, you don't need to create a new one. Just open it
3. Put these snippets on the file
4. On line 7, please change 'yoururl' with any URL you want. And then save the file.