Before you start backup your htaccess file and be careful – dont block your ISP IP address or your own Ip.
Blocking ip addresses with htaccess :
For blocking entire country visit http://www.find-ip-address.org/ip-country/ or
for automated generated htaccess, then open htaccess with NotepadPlus or similar editor select all, copy and paste in your htaccess and upload to server.
Change or add IP addresses to match your choice .