Starter replacement instructions please?

Hi. I have a 2004 Chevrolet Blazer 4.3L, it's an extreme version, but I don't think that matters. Okay, here goes an issue I'm having now. Thought started went bad because it stopped working. But at same time my vehicle quit working while driving, it stalled out while idling first though, but the starter was bad after testing of it. Now I've replaced the starter. No luck. I don't know the problem and there is so many possibilities. When I turn key to on, nothing comes on on the dash but A/C and lights are working. But no power anywhere else. Also, the scanner things to tell you problems with your vehicle won't even power up when plugged in. I'm not a mechanic but I'm not slow. Someone please point me in the right direction. Thanks