quick! how to use includes?

I am starting to build a web site for a new client and I would like to use includes for the navigation (the site will be several pages so this will make it a lot easier for me). I've used includes before, but was never in charge of "setting them up". What needs to happen to get them to actually function? I can't save the pages as .html files, can I? Don't they need to be .asp or .shtml? I'm building the site using Homesite and will publish it to the client's server. Do I need to contact their ISP to set any of this up for me?

Sorry, I'm a beginner when it comes to anything other than HTML!

You'll indeed need something more then html for this
What you need to know is what server-side scripting your client's ISP is allowing (like PHP and/or ASP). With that information you'll know what language you have to use and then you can come back and ask how to do it in PHP, ASP, ... here...

Don't worry, as long as their ISP is a bit up to date this won't be difficult or take long

Not an ideal solution, but you could also just use a javascript include, though I would go with asp or php or if your client's isp supported shtml - any of them

Thanks everyone. I called the ISP and it looks like I can just save my files as .shtml and go that route....

Using shtml for includes would be new to me since it simply is a secure html page. In all likelyhood your host will allow php (maybe even ASP). Using includes in php is pretty straightforward.

SHTML is not secure HTML. SHTML is the code for SSI HTML documents. There is no such thing as secure HTML as it has no concept of security at all, its document formatting. It can be transmitted using a secure HTTPS connection but that happens independant of the HTML itself.

Sorry, you are right offcourse. I had a brainfart and got shtml mixed up with the ability of the host to use https.