Theme frustrations

I would quite like to add this pointer as the one on my account:
https://i.postimg.cc/dtn0QGFb/left-ptr.gif

I've tried a couple methods, and got a bit frustrated. It's been so long since I messed with HTML that I forgot how to do basic things, but I'll figure it out. I don't really need help, I'm just expressing annoyance, but I wouldn't reject help if anyone gave it to me.