WordPress MU

How do I upgrade my mu wordpress instalation?
In admin a click in "upgrade" botton but it seemsn than dont work :(
In all pages:
<meta name="generator" content="WordPress wordpress-mu-1.2.3-2.2.1" />
I want at lant 2.6.5 :)

Did you upload new files?

tried that route too. he he. it seems that you would have to follow the instruction here first:

http://codex.wordpress.org/Upgrading_WPMU

after doing all that, then you can click that upgrade button. :)

I need to upload files?
i dint't know.. a think the upgrade bottom does everything...
I upload new files for where? Overwrite the old files?

Thanks alunsina for the link
what version do I have? 1.2.3 or 2.2.1 ???