How to change the table header, table rows(Odd Row/Even Row) CSS in Helpdesk/Categories displaying table?

What do you mean by your question? To change the description of the column you have to change things in the code. But it might be better to post a new question, because that is not related to the original question.

openerp@testdev:~$ /opt/openerp/server/openerp-server -c path_to_config_file -u crm_helpdesk Usage: openerp-server [options]

openerp-server: error: The config file 'path_to_config_file' selected with -c/--config doesn't exist, use -s/--save if you want to generate it openerp@testdev:~$

Perhaps you used "path_to_config_file" literally? That file must exist on your system, you need to first generate it. Stop your openerp server, then start it with "openerp-server -s -c <config_file_path>" , replace <config_file_path> with f.e. ".my-config" to create a config file in current directory. Then start server as described in my answer, only without "-s" and -c .my-config (if starting from same directory where your config file is).

I mean when you have generated your config file, start server with "openerp-server -c .my-config -u crm_helpdesk , this is documented in version 6.1 install documentation at http://doc.openerp.com

Thanks...... Where the code found in list view and form view for Helpdesk/Categories?

Don't know, sorry. That should probably be a separate question.