Programming ATMega16L over ISP interface
For ISP programming you only need MISO, MOSI, SCK, RESET and GND.
The Vcc connection is optional, if the programmer can supply Vcc then you can power the board from the programmer.
Note that the two Vcc should never be connected if they are both active because you will create a short. When you power the board from the programmer make sure to unplug the mains supply of the board.


  where do I connect TxD, RxD, SS pins of target ISP header.


There is no need for these in ISP mode and normally they are not part of the ISP plug



Note that some programmers



I'm adding the connection scheme that should be followed for the ISP lines.

The pins involved are:  


MISO : Master In Slave out  
MOSI : Master Out Slave In  
SCK: Clock  
RST: Reset
GND: Ground  
VCC: Power supply (optional, if used the board mains supply should be disconnected. Also make sure that the voltage levels match, 5v or 3.3v)  




MISO/MOSI lines should not be cross connected. MISO is an input for master and output for slave and MOSI is output for master and input for slave so MISO connects to MISO and MOSI to MOSI.