There are code snips and what not at the top of our donation pages....and people cannot donate. Help!
Andrew West's comment seems to be correct. There are two different things happening here - or three, depending on how you look at it.
The most important is "Permission Denied". I just visited your site, and confirmed you're running Drupal as your website software. Go to this page: www.mcuw.org/admin/people/permissions. In the "CiviCRM" section, find "CiviContribute: make online contributions", and make sure that it's checked off for both "Anonymous User" and "Authenticated User". Note that you'll need to be a Drupal administrator to view that page; if you're not, please contact your website administrator.
Second - you're getting notices on the top of the page. Those notices shouldn't affect anything, but they're bad for the donors to see, it erodes trust. You should hide those. A good explanation of how to do that is here.
Third - I'm not sure why you'd be getting those notices at all. You may want to ask your website administrator if there are any customizations they can think of that might lead to those notices appearing.
You need to contact your hosting company to resolve. United Way has vendors (OneEach Technologies, etc.) that provide website/hosting/civicrm packages to many UW affiliates that manage the backend configuration of your website.
You do not have the permissions to make the changes needed to fix this. Your hosting company does.