Error using jomsocial plugin

Looking at your website the return URL should not produce any error.
For the cancel URL, you should do the same modification:
$cancel_url = 'salsamundo.v3.salsamundo.eu';

For the description: it must be a conflict between the HTML editor and the browser

Hello !

I changed it, refreshed the cache and still the same issue

$return_url = 'salsamundo.v3.salsamundo.eu';
$cancel_url = 'salsamundo.v3.salsamundo.eu';

I've just refunded your monney

You need the http:// in the URLs.

$return_url = ' salsamundo.v3.salsamundo.eu ';
$cancel_url = ' salsamundo.v3.salsamundo.eu ';

It's just my copy/paste which removed them.

I tried to access your shop but it seems that you removed the products display so I can't test.