How to do that:

1) Open your steam folder, navigate to \resource\layout\ folder2) Find overlaydesktop.layout file and open it with any text editor. The file format is similar to JSON.3) In the text editor, in "controls" section, add following line:BookmarkID { controlname="URLLabel" labeltext="Your bookmark name here" urltext="your page URL here" style="sidemenu"} BookmarkID is something that you will refer this bookmark in next step4) In "layout" section, add your BookmarkID to the list in following line:place{controls="GameGroupsButton,ChatRoomButton,DLCButton,GuideButton,,WebSiteButton,RecommendButton,WorkshopButton,Your BookmarkID here" y=50 align=right region=overlay dir=down spacing=10 } 5) Save the file and you're done!