WordPress MU

Hi,
after the installation of a new theme I tried to put the banner ads into the header (header.php or theme functions.php).
But I must have done something wrong, now I can't access my site anymore.
All I can see is the following:

Parse error: syntax error, unexpected T_STRING, expecting ')' in /home/ca10gn/public_html/wp-content/themes/wpspidernews/functions.php on line 189

So what could I do now?

Thanks and sorry, it's my first wordpress blog!

You have an error in the function.php of that theme. To "fix" it you can track down what's wrong on line 189 of that theme, or delete the themes/wpspidernews/functions.php theme on your server. Other stuff in the theme will probably break, but you should at least be able to get in and switch to a working theme.

Thank you very much, but I can not delete the theme because I cannot access the wp admin area.
I mean how can I go to my wordpress control panel to delete the theme?
I'm so lost with this!

Because you inadvertently "broke" your theme's PHP files, you won't be able to access the WP Admin area until you remove the offending theme.

The quickest way is using an FTP client or some other mechanism that lets you get directly at the files. Just browse to the theme directory and either delete the whole theme, or replace it with the previously working copy.

Another alternative is to rename functions.php to _functions.php. You should be able to access the admin area and edit the functions file if you do that.