First I am not to good with writing tutorials so bear with me.
The Goal of the game is to kill off the entire world's population with your disease.
After you've selected the type of disease, named it, you'll come to this screen:

Now to explain the points.
The world map you can scroll around by using the red box. This will show you
the current status lvl of each area. The redder it is the more infected that portion of the
world is.
The News Box. This will show you flash updates as to what various countries are doing
to slow the progress of your disease.
Evolution points. These are points you gain, through time, based upon the evolution of
the disease. These are pretty much your money that you use to buy attributes for your
sickness.
The Time Slider bar: Controls the speed at which your game progresses.
The first thing you'll want to do is turn up the time slider to the max point. The game will
progress way to slowly.
Then click the disease tab which will bring you here:

Each tab here you can buy with your evolution points.
The symptoms are self explanatory, and control how fast your disease spreads.
Careful how many you purchase, as the faster it does so the more likely the world
will react according and eventually build a vaccine.
Resistances: These are the various resistances you can build up to further spread the virus.
Each resistance is pretty self explanatory, ie moisture will help it stay alive better in wet climates.
The Drug resistance is very important as it will slow the vaccine development.
Transmission: Determines how your disease is spread. Through the air, bugs, rats, or in the water.
These are your best weapon so use carefully as the world will react accordingly. If its airborn, and
spreading fast the world will close its airports.
Once you have spent all your evolution points close out the disease tab and return to the world map.
This is the only map you can be on to earn more points.
At any time, while on the world map, you can click the world tab.
This will bring you here:

This is your status screen that tells you what countries you've infected, how many are healthy vs infected, dead count ect ect.
The best advice I can give you is be as little as visible as possible, for the longest time. Hopefully that will ensure your infection of the entire world, then upgrade symptoms to a lethal lvl and kill em all!!!