Save this example to the tcl library as specified in your tcl library configuration. From the example configuration given this would be:
/var/www/alpha.co.uk/tcl/init.tcl
ns_register_proc GET /index.html hello
proc hello {} {
set set_id [ns_conn form]
set param_value [ns_set get $set_id foo]
ns_return 200 text/html "Hello World. Value $param_value"
}alpha.co.uk/hello.html?foo=<value>
Output:
Hello World. Value <value>