How do I do this please

[kat]

Ta, Arantor.

Not straight away, no. But, Google'll get there, soon enough.

[MrPhil]

If you change the file as indicated, that will immediately change the page title as seen in your browser. However, Google et al. will not show any change in your listing until the next time they crawl your site. That could be anywhere from an hour to a month.