This is pretty easy to do. You already have the code for sending the message, it's just a matter of substituting the name.
There are many ways to do that - some simpler than others. You might prefer to have the script read from Excel directly, or you might prefer to export the data as a comma-delimited text file and have AppleScript read that - lots of options.
Then just break your script down into critical parts - in this case one part to extract the data from excel/file/wherever; one to send the message; and a control loop.
You might end up with something like this (untested):
on get_member(id)
tell application "Microsoft Excel"
-- assumes column 1 for the name and column 2 for the phone number
set _name to value of cell ("A" & id)
set _number to value of cell ("B" & id)
return {name:_name, number:_number}
end tell
end get_member
on send_message_to(member)
tell application "Messages"
try
send "Hello, " & name of member & ", This is text" to participant (number of member) of account "SMS"
end try
end tell
end send_message_to
set i to 2
repeat
-- go get the data for the member
set _member to get_member(i)
if name of _member = "" then
-- break on the first empty/missing name
exit repeat
end if
send_message_to(_member)
-- increment the counter
set i to i + 1
end repeat
