Hi there,
I am also a newbie but I have recently put this sensor to work.
My first question would be: do you have the 3 or the 4 pin version? Remember that the 4 pin version requires a resistor (the 3 pin one has one built-in).
I also got this issue when the cables were loose (for example, not connected to a bread board).
Remember that this sensor has a temperature accuracy of +-2 C when you are testing raising the temperature and a delay of 1 sec minimum between readings.
I found everything to be well explained in this tutorial. He also shows how to attach an LCD and make it work with the sensor, which I assume is your next step.
http://www.circuitbasics.com/how-to-set-up-the-dht11-humidity-sensor-on-an-arduino/
I hope it helps, but I am also a newbie here.