Once the box is flashed your should see the openATV setup wizard, it starts with selecting your video resolution for your TV. The box will sit at 49 on the counter at this point. If you don't have anything on your TV screen at this point then this needs to be sorted before anything else.
The Infinity setup instructions show a screen shot of what you should see once your box is flashed with openATV.
Webif is done via your browser on computer, tablet or phone, but as above, you should already have something on your TV at that point.