New to desktop builds-need advice/knowledge

So, going to try and keep this fast and simple:

I currently am running a Gigabyte GTX 750Ti, 350 watt PSU (prebuilt refurb).

I am looking at stepping up to a better GPU, but have no clue as to what each spec means and the different families of GeForce processors. I'm thinking about going for one of the 1060s or a 1050, but what makes them better than something in the 800/900 family?

Basically what I'm asking is what is the TL:DR of GeForce GPUs and desktop part buying in general