A bookmarklet is a "one-click" tool which adds functionality to the browser, such as modifying the appearance of a web page, querying a search engine with search terms provided by previously selected text, or submitting the current page to a translation or blogging service.
They do basic tasks on clicking.
They are universal, i.e. they usually work on any browser, and whatever the platform, mobile or desktop.
They are managed like any bookmarks.
Drag the bookmarklet from the page to your Bookmarks Toolbar. It should appear on the toolbar.
All you have to do is:
Navigate to the page where you want your bookmarklet to apply to.