I don´t understand where to use word diye. I know we use it with direct and indirect speech. But also I´ve seen it in daily conversation many times. But I´m not sure if it was direct or indirect speech. 
Something with werb sormak .
Diye sordu.. etc.

Thank´s in advance.  

validen ?

1. use. (indirect speech) with sordu.

Ahmet "yarın geliyor musun?" diye sordu.

2.use because or because of

Pahalı diye tişörtü almadım. ( i didnt buy the T-shirt because it was expensive )

3. use called

Seni Mehmet diye birisi arıyor. Someone called Mehmet is looking for you

Be proactive!

type "diye" in the search box and hit ENTER or click "Search" (the rightmost text on the top bar) and you should get many similar threads with some good info in them more than you expect for.

@Teacher- Thank you so much!!

I´m sorry mister si++ , I didn´t know about search box,thank´s for letting me know.