5
Log into the admin panel and create a custom block.
Make sure it is set to be visible, and select the placement (centre, I would imagine).
Type your title in the text area (Welcome to my site! or whatever) and then below that, type your front page welcome message.
Set it to auto-format if you are just typing, not using HTML... click save!
It's very basic.
NOW having said that...
If you don't see it where you want it, check the blocks menu in the admin panel and make sure that the custom block you just created is set to centre, set to visible, and set to TOP PAGE.
That should do it.
Hope that helped!