Hello $nick $+ , Your message has been recieved....
For that as yuo have been told already its
set %line Hello $!nick $!+ , Your message has been recieved....on ^:OPEN:?:*: { msg $nick %line }
For this i beleive you well find you need to use
on ^:OPEN:?:*: { msg $nick $(%line,2) }other wise you really well send "Hello $nick $+ , Your message has been recieved...." to the nick.