assuming the nick is the first word on the line:

on *:TEXT:.searchmember*:#: {
if ($read(members.txt,w,$+($2,*))) msg # $2 found
else msg # $2 not found
}

note: the # in the eventline indicates a channel, use a = for a dcc chat or a ? for a query
when using a query, replace msg # with msg $nick
when using a dcc chat, replace msg # with msg =$nick

DALnet #Helpdesk
I hear and I forget. I see and I remember. I do and I understand. -Confucius