Please help me combine the two codes for DHT11 and SW-420 Vibration sensor for arduino in one program
There are multiple threads on how to combine two different sketches. One of the main things you have to do is refactor your code to get rid of calls to delay(). Do a Google search on Arduino blink without delay and read one of the tutorials you find. The idea is to make a call to the millis() function for each thing you want to do on a time intervl, save the current millis count, and then wait until the new value of millis() is greater than the saved value by your desired time interval. By doing that, your code does a very fast series of checks: 

"is it time to do &lt;thing 1&gt; again?" 

"Is it time to to &lt;thing 2&gt; again?" 

"What about &lt;thing 3&gt;"

And repeats.

Then it doesn't freeze the rest of your sketch waiting for time to pass. (That is what delay() does. Everything stops until the delay time has passed, which is bad.)