DHT.h Library not being imported
Download https://github.com/RobTillaart/Arduino/archive/master.zip
Copy the Arduino-master/libraries/DHTstable subfolder of the downloaded file to the libraries subfolder of your sketchbook folder. You can find the location of your sketchbook folder at File > Preferences > Sketchbook location in the Arduino IDE.
Change the first line of your sketch from:

#include &lt;DHT.h&gt;


to:

#include &lt;dht.h&gt;



Now when you try to compile the sketch you will still encounter many errors. However, these are caused by a paucity of semicolons, not by the DHT library, and thus off-topic for this question.