One of the things that Project si very good at

I dont know what version of project you are working in, so the mechanics may differ. If you go to calendars, at the bottom of the dialogue box you will see "Exceptions". Put in the start and finish dates of the non- working time, name it as you wish, and it will then show on the chart, along with not allowing tasks to be carried out on these days.

I am assuming you have not created any special calendars, and are using the default, if this is not the cae let us know and we can run through altering several calendars.

In Project 2010, go to the "Project" tab and select "change working time".
In Project 2007, go to the "Tools" tab and select "change working time".

Dont have versions prior to this Im afraid, but a quick run through the menu tabs should give you a similar option.