I want to flash ex9r to my FlySky TH 9x transmitter. I can see people have used USBasp AVR Programming Device http://www.hobbyking.com/hobbyking/store/__27990__usbasp_avr_programming_device_for_atmel_proccessors.htmlto flash er9x onto transmitter by soldering 10 pin IDC connector to transmitter motherboard.
 I just wanted to know if anyone has done this earlier and what all tools/things I need to collect to do this.

I have done this many times, you need that usp asb programmer, few thin wires, soldering tool and good soldering skills as the soldering area is very tiny

This is the video which i followed and had helped me a lot

I too flashed mine for the first time a few days ago it's not as difficult as it seems...

Later with that confidence I tried the Frsky telemetry mod and I don't know what went wrong...  I don't get any display...  I guess I have burnt something from the processor while soldering directly to the IC...
Any guidelines Satya sir?

Any idea where can I get 10 PIN IDC connector?

10 pin connector is commonly known as "Box Header". You can get this from any electronic component store, costs Rs3 each. You have to solder 6 ISP wires (MOSI, MISO, SCK, RST, VCC, GND) between board to the header. I have flashed my Flysky Tx with Open Tx recently without any issues  .

http://www.rcindia.org/radios-and-receivers/%28help%29-fs-th9x-orange-rx-compatibility-er9x-flashing/

Just refer the thread,you may find something useful if you get confused.

Its not absolutely necessary to have a connector, because you would only be flashing firmwares occasionally(once/twice a year at max).I had inserted some male jumper wires into the programmer(and taped them) and soldered the other end directly on the Tx. After completing the process, just tucked those wires inside the Tx and closed it! And trust me I never felt the need to upgrade it further, because it has everything I would ever use while flying.

Will the 25watt soldering iron tinn the transmitter points without damaging them? Or do i require lower watt soldering iron to do it?

anything will do the job.

Try to flash it again, check the connections properly, make sure that you are soldering the right spot.

Thanks sir will try that

thanks for help..
Any tips for tinning main board solder points? I have 35 watt solder iron.

Use one with a smaller tip and I would suggest use a 12 volt soldering iron used for mobile repairs... As I did...  Works good
All the best