If you are using Internet Explorer drag any of the following links (choose the desired language pairs) into your Favorites. If your Favorites are not visible on the left side of your browser, click on a star in top right corner. Maybe you will have to pin window to a sidebar by clicking on an arrow. Users of Mozilla Firefox need to drag the link onto their Bookmarks Toolbar.
Double click on word to select it. Then, single-click the button (Firefox) or link (IE) of the corresponding language pair to translate the word in the same window. If you forget to select a word, a text input field will be displayed. See this screenshot: Bookmarklet in Chromium