My dedicated server uses Red Hat 7.0, Plesk.
I need to add this following line:
AddType text/x-server-parsed-html .html
Since i had no telnet access, i tried to use .htaccess file. After uploading that file, i got an internal server error. Could anyone help me solving this problem. Thank You.

try
AddHandler server-parsed .html

Tcoy,
It still the same, 500 Internal Server Error.

Yep, use SSH :)

My suggestion

1. Check /usr/local/plesk/apache/conf/httpsd.conf.def
2. Search for: <Directory "/usr/local/plesk/apache/vhosts">
3. Change the AllowOverride directive in there to:

AllowOverride All

4. Reload apache with /usr/local/plesk/admin/utils/./my_apci_rst

Micro,

Could you tell me how to reload the apache.
I am now at /usr/local/plesk/admin/utils/./
when i type my_apci_rst and press enter, i receive this message :
bash: my_apci_rst: command not found.
Thank You.

Just type

/usr/local/plesk/admin/utils/my_apci_rst

and then enter

General tip: When you get "500 Internal Server Error", read the error log file and it will tell you more information. Common places where the error log file could be:

/var/log/httpd/error_log
/usr/local/apache/logs/error_log

or the domains logs located at

/usr/local/plesk/apache/vhosts/domainname.com/logs

domainname.com = true domain name

Problem solved.
Thank you to all of you.