Graphical Element inside Page, Post or Widget

Hello,

I need your suggestion for a case.

In many occasions, customers ask me to include some graphical elements inside their website. For example, one said he needs to have something like “sticky note” with shadow inside pages to be able to write some important information visibly for the visitors. I didn’t know what should I do because there is no plugin for everything.

How can I design such elements myself and use it?