There are lots of online videos out there, and I'm sharing my favorite one so far here, that shows how to wash your car properly in a pretty comprehensive way. It's done by Mike Phillips, a celebrity in the car detailing world. I like his articles and videos because they are well composed and simply make sense. Enjoy this one!
One thing that I'd like to emphasize is the usage of a good wash mitt, because I see a lot of people use traditional sponge which can scratch paint (or even worse: chamois!). But if you feel like a lambswool mitt is too pricey to start with, there are actually other choices you might want to check out. How dirty is too dirty to safely use a rinseless wash? is another nicely written article by Mike Phillips which also lists some alternatives to choose from to replace the traditional sponge.