HTTPS mixed content warnings

When I load my page via HTTPS my browser gives me some mixed content warnings. The following ressources are trying to load via unsecured HTTP:

http://$URL/wp-content/plugins/bbpress/templates/default/js/editor.js?ver=2.5.3-5249
http://$URL/wp-content/plugins/user-access-manager/js/functions.js?ver=3.8.1′
http://$URL/wp-content/plugins/user-access-manager/js/jquery.tools.min.js?ver=3.8.1
http://$URL/wp-content/plugins/user-access-manager/css/uamLoginForm.css?ver=1.0
http://$URL/wp-content/plugins/user-access-manager/css/uamAdmin.css?ver=1.0
http://$URL/wp-content/plugins/bbpress/templates/default/css/bbpress.css?ver=2.5.3-5249

http://ww.wp.xz.cn/plugins/user-access-manager/