Definition, anywhere on article, likely ideally as the first usage:
<ref name="myname">{{cite web ...}}</ref>
And then you can use it later on as:
<ref name="myname" />
which automatically expands the exact same thing, or using the shortcut:
{{r|myname}}
To cite multiple pages of a book: en.wikipedia.org/wiki/Wikipedia:Citing_sources#Citing_multiple_pages_of_the_same_source, the best method is to define and use the reference without adding the p or location in cite as:
<ref name="googleStory">{{cite book |title=The Google Story}}</ref>{{rp|p=123}}
Do not set the page in cite, otherwise it shows up on the references. Instead we use the {{rp}} template. And then use the reference with the {{r}} template as:
{{r|googleStory|p=456}}
or for multiple pages:
{{r|googleStory|pp=123, 156-158}}