Because you're working with floats, you need to define numbers with a decimal place. The error occurs because when 5/9 is calculated, it returns the result as just 0.
So change numbers like 32, 5, 9 to 32.0, 5.0, 9.0.
For aesthetic purposes as well, you could also change the lines of code that deal with conversion to just a single line:
kelvin = 273.15 + ((fah - 32.0) + (5.0/9.0));
cout << "Kelvin: " << kelvin << endl;
A good site to get help with for C++ is either stackoverflow or dani web, or just shoot me a PM whenever and I'll help with what I can. You'll get your head around C++ soon enough.