Can you please explain what you mean by "...no proper communication between dac ic and atmega." The ATmega16L has a rather capable SPI serial interface that is well documented in the data sheet, and you have already referenced the TLV5624 DAC data sheet which contains a timing diagram.
You will need to configure the SPI peripheral so that it sends the data and clocks as required by the DAC and then start sending the data.
Once you get the basic concept of the SPI interface (that the master exchanges values with the salve) then it is relatively straight forward.
Perhaps you should show us what you have written so far, what it does correctly and what it does not do that you expect it to.
Susan