You type in your location latitude and longitude, which you can find here and it comes back with flybys of the various satellites that will pass over your location, it gives you the start and end times, the altitude and magnitude, plus a couple maps. The map above was the one I used for the ISS last Saturday. I knew that at 9:23 pm the ISS would rise above the west horizon, it would reach it's max altitude in Gemini around 9:28 pm, and then disappear into the shadow of the Earth shortly after, it also tells you how high it is, the flyby that night was at 372 km.
So of course it's cloudy, even though the weather network says it isn't, I go out to my spot just in case it isn't cloudy out there, or maybe the clouds will fly away by the time I get there. Get to my site look to the sky, and there are clouds. They don't look to be moving out of the way anytime soon. I'm about to go back to the car to leave and I notice the star Sirius trying to burn through the clouds, and think the ISS is much brighter and bigger, it might work.
So after some experimenting with f stops, exposure rates and the ISO levels, I come up with a combo that brings out the stars that are trying to burn through the clouds without over exposing the image, just in time, I notice the ISS rising above the west horizon, take a pic, 15 sec exposure, anything longer would have overexposed the image due to all the clouds
I was able to get 4 pics before the ISS disappeared into the Earth's shadow, the image above. The ISS is looking especially bright these days with all the additions like the Columbus Laboratory giving it more overall surface area for Sunlight reflection. I'll leave you with a video I put together of the images I took of the ISS flyby.