How secure does it have to be? You're not storing customer credit card information or social security numbers, etc, are you?
If it absolutely has to be secure, use SSL (https) and consider using a packaged authentication system (Apache's mod_auth_* comes to mind) rather than building a custom system. The reason I say this, if security is imperative, you're better off using a system that has been tried and tested, plus having a group of developers looking at the code for holes helps (unless of course you create secure auth systems as a hobby).
If you don't want Google or other search engines to index the pages, just create and edit a 'robots.txt' file or use the meta tag in your HTML to keep robots from indexing.
No, I'm not storing or collecting any credit card informatio. Just contact information and some information of services what customers have ordered.
Little about my system tho if it helps for helping.
I have dedicated server and I have installed plesk on it.
I have read something about SSL certificates and thinking of buying one?
So, if I buy on of these SSL certifications, could it be so simple that when I receive one, then install it via plesk my pages would be secured?
Anyway, thanks for replying SOCK and about that robots.txt: I use already that file but somehow I have this fealing that it's not stop those crawlers? Or is it that powerfull? ;)