replace tiny mce with ckeditor in joomla

I have a joomla project. In this the text editor is tiny mace. But there is no option to up开发者_开发百科load a pdf file. So I want to implement Ck editor or fck editor instead of tiny mce. I have downloaded ck editor and install as usual way (admin side ->extension->install- uninstall section) and disabled the tiny mce in Plugin Manager. But I can't show the editor; I think I am in wrong way.

Does any one have any idea? Please help me.

Got to Site > Global Configuration, make sure you're on the Site tab (usually comes up by default), then select CK Editor from the dropdown for Default WYSIWYG Editor.