I think you are confused with what should be edited in nagios.
You should leave the command definition how it was, something like:
# 'check_http' command definition
command_line $USER1$/check_http $ARG1$
The $ARG1$ means that when you create a checkmyhost.cfg file any arguments to pass to what you want to check goes to it.
So in your checkmyhost.cfg file (name it whatever you want, just make sure nagios.cfg points to it by cfg_dir or by cfg_file)
you then would define a service
use generic-service ; Name of service template to use
service_description my localhost http site on port 80
check_command check_http!-H localhost -e "HTTP/1.1"
I think your problem is you weren't even using a defined service, you were modifying the definition of check_http so it would alert you immediatley. Create a checkmyhost.cfg or whatever and define a service to check for it per my example above and you'll be fine. oh and fix your defintions to use the variables again instead of hard coded values.