Hi Angel
I also had trouble with tinyMCE
See :-
http://modxcms.com/forums/index.php/topic,47621.msg279609.html#msg279609
Maybe will work for you.
DEVELOPMENT ENV:- Ubuntu 12.04 | MODx Revolution 2.2.8 | LAMP 2i Apache 2.2.22 | Php 5.3.10 | Mysql 5.5.31 MySQL client version: 5.5.31
I just installed Revo 2.0 rc1.
It did not come with any rich text editor enabled or installed.
I installed TinyMCE from the package manager without errors. I enabled it in system settings:
Editor to use: TinyMCE
Enable Rich Text Editor: Yes
But, when I edit a page or a template, it’s still not there.
I tried uninstalling and re-installing it, but to no avail. Any suggestions? I’m not stuck on TinyMCE, any rich text editor will do fine.
Try CKEditor

works great here
Ok, yes, I can confirm that CKEditor works fine, but not TinyMCE for me in 2.0 rc1.