Usually you have in each object the possibility to enter a help-text under Properties -> Caption -> Helptext. In most cases you will then have a "?" displayed in the title-bar, when hovering with the mouse over it, your text will show up. You may also qlik on it. For Text-Objects it works also without title-bar.
I'm not sure if's a setting thing, but I cannot find this Helptext option. I looked at the user preferences to see if there was something I needed to activate but to no avail.
