Domain issue

Hi,

I’ve installed wordpress on this domain.
http://109.70.4.200/~management/

Now I’ve pointed the url: http://managementplatform.nl to it.
How can I make it happen that the URL is set to managementplatform.nl?

Because it stays at http://109.70.4.200/~management/
When I change this in the wp-config file I get a database error.

Any help would be very nice.
Thanks.