Change a couple of things:
Move these to the top of the sketch
#include <dht11.h>
#include <VirtualWire.h>
Delete this unless your transmitter needs a Push to Talk switch (most don't)
vw_set_ptt_inverted(true); // Required for DR3100
put the data you want to send in an array
msg[ ]
then virtualwire will send the msg[] array out.
I can't tell what data type you want to send - DHT11.temperature is a float? thus 4 butes?
So put 4 byte in msg[0] thru msg[3] and let 'er rip.