[Koha] Koha Installation

[Shiju Thomas]

Dear sir,

I am trying to install Koha in my system(Linux platform).But it is not being
installed.

It is showing a message :

System maintenance

The Koha online catalog is offline for system maintenance. We'll be back
soon! If you have any questions, please contact the site administrator

That is why I have sent this mail. Why is it not being installed. Please
provide help.