Project files! Help please

Hello there,
I am not expert. I installed the plugin on my wp 3.5 but I can’t see the box to add files.
I tried to reinstall it but does not work.
I also changed in “wp settings” to 2 columns as suggested http://ww.wp.xz.cn/support/topic/plugin-collabpress-project-documents-1?replies=7 but does not work
Can you help me?
Thanks and great plugin by the way

http://ww.wp.xz.cn/extend/plugins/collabpress/