I bought some concrete mix where I add water and then I should smooth it on but it didn't smooth out. Looks like pieces of stone or small rocks. How long should it take to mix concrete in a wheelbarrow?
It sounds like you are trying to spread it on to thin. The stones should sink and you should have a layer of 1/4 inch or so of concrete without stones. You have to smooth the surface of the concrete with a trowel.