Setting up CKeditor for Drupal 7 is unfortunately not a trivial task.
You provide too little detail about what you've done and not done for us too be able to debug your installation for you. There are many stumbling blocks, such as knowing the difference between the stand-alone version vs. the one based upon the the general WYSIWYG module. Note: they're not compatible. Another stumbling block is getting the right version library in the right place, etc.
However, having recently struggled with setting up CKeditor for Drupal 7, I decided to write up a detailed recipe for the provess for setting up stand-alone CKeditor. I have double checked it from a clean Drupal 7.26 install to verify that it is complete.
In brief, the steps are:
- Installing and enabling the stand-alone CKeditor module that interfaces the editor to Drupal.
- Download and install the CKeditor itself.
- Downloading and enabling the WYSIWYG Filter module.
- Configure a custom wysiwyg text format.
- Create wysywyg profiles and attach them to suitable text formats.
- (Optional: Configure picture upload method).
Hope this helps!