How can i make a custom message in msn 7 like Appear Online, Offline, busy etc....I wanna make a custome one any idea how?

Thanks

You can't add or edit existing statuses, not in any version of MSN Messenger. With Messenger Plus! you can use custom statuses; if this is what you are looking for, then you will have to wait until Messenger Plus! 3.40 is released in a few days; it is partially compatible with MSN Messenger 7

How will they work in shortcut keys or how?

They are just the basic custom statuses you can use already in Messenger Plus! (just not on MSN Messenger 7).

For more information on how to use this feature, take a look at the personalised status tutorial.

More detailed information: say you change your status to Away and use the personalised status "Fishing", you will see your nickname as
Normal name {Fishing} (Away)
on the top of the contact list.

Someone with Messenger Plus! installed will see
Normal name (Fishing)
in their contact list, where (Fishing) will replace the (Away).
You can test this by adding yourself to your contact list.

Someone without Messenger Plus! installed will indeed see
Normal name {Fishing} (Away).