add a custum page to cms?

[Amit86]

ive been looking whole day now
is it even possible to add a custumized page to the cms system?

I mean,
i have a few non-integrated systems besides the forum system
such as signature makers, statistics etc,
i want to be able to add them as single pages to the CMS system,
how can i do that?
also make a link at the side menu (sidebar) that when i use it will link to them on the center content colum?

Also,
If there's a holiday i want to be able to make a new "announcment" on the main page where i could see the whole page i just wrote and not half of it, how is that possible?