The web servers are configured to look for a matching file name to use as the default home page. In listed order, they are:

default.aspx
default.htm
default.asp
index.asp

By default, the "Under Construction" page is named default.htm. To make your homepage the default page, either name it default.htm and overwrite the existing file, or delete default.htm and name your according to the other acceptable file names.

A complete discussion of your default website can be found here at the related link below.