please how do i create a welcome note when i put on my montage 8

Please, what is a "welcome note"?

I'm assuming the OP is looking for something similar to the EX5 user-editable greeting message.

http://www.cyborgstudio.com/synthmp3s/yamaha/ex5/manual/ex5ownersmanual.pdf

Page 277

[F7]: MSG (Greeting Message)
Sets the message that will be momentarily displayed in
the screen when the power is turned on. The message
can be up to a maximum of 20 characters.

Montage does not have any such thing that I am aware of.

However, if you default to Live-Set on boot-up you can customize the text of the first Live Set entry as a sort of welcome message.

If you default to the performance home - I believe the first user position for me is the default recalled performance - so you could edit the performance name as a sort of welcome message.

Not exactly the same - as a welcome message - but not sure exactly how you're intending on using this (identify one keyboard from another in a multi-Montage setup, tell your boards apart from rented equipment, etc.). If identification is the main purpose - you could go low tech and put a sticker under the keys (black metal along front side of keyboard) or somewhere you can see the sticker quickly. Maybe there's a different reason.

thank you