I’ve just install joomla at my account and everything works perfect on the back end. Except the article manager,so I can not write any article to put on my site,everything else (templates,plugins,menus) works perfect.

Can you help me?

please read the (install)documentation, my guess is you either haven't set a file permission right, or haven't set a file path right.
might want to check your .htaccess file aswell.

not much info to go on, but those are typical problems.

The permissions are set to 755 as they are on default.

Where I can find that documentation?What about file path,and where is .htacess file?

Sorry for all thes,I know I am a little bit newbe....

When I click on Add new article on Joomla's back end I send to a blank page with this address: http://-------------------------.---/ad ... om_content

I had the same problem ...
Check with your hosting company ...
Vtiger might not be compatible ...
I changed and it worked after ...

not much info to go on, but those are typical problems.