Plugin to insert text at current cursor position

Is it possible to simply insert text at the current cursor position?

I'd like to insert the current date and time and a few other bits and pieces, essentially using Sigil as a fancy journal system. I can handle formatting the inserted text myself, but if someone can clue me in as to how I can simply insert 'Hello World!' at the cursor position, I'd be very grateful.

I have tried with the documentation, but I'm struggling somewhat… the learning curve is a little steep, and although I've downloaded a number of example plug-ins for tips, I've come up short.