Question : Set up a test environment for sharepoint server 2007

I am new to sharepoint.I am doing some sort of customization of pages.Problem is we are having a demo server and a backup server.NOw whatever iam changing in the demo or backup servers are effecting the original sites.So i want to setup a test environment,through which i can enhance the site if every thing goes fine i can apply them to demo server.

So i want to know how can i setup a test environmentfor this.Iam using sharepoint server 2007.

 Please very urgent

Answer : Set up a test environment for sharepoint server 2007

I tried up this and got vexed up as no solutions worked.For this time i want to close the question.I don't want to waste experts time on this.