I have creaded files header.html and footer.html and now I to place these on all my website pages. so the header and footer will be the same on all my web. Please tell me how to include these two files in simple HTML pages?

You can't

It needs to be a .shtm(l) (or .php, .asp ) page to include other pages in it

alternatively your server would need to be configured to allow SSI (Server Side Includes) for .htm(l)

This could be a simple task (or complicated) depending on your server technology.

Thanks chrishirst

I'll try to do it with .php