In which place i incert a sim card

First of all, check the device's power is off. Then open the sim card slot and place the sim with gold plating downward and close the slot. You are good to go with your tablet.

Hi
please do these tips :
insure that your SIM card working properly test it in another phone

if it work so clean the SIM card place , and test it while you push the battery to keep SIM in its place .

if that don't help try to software the device .

if that don't help so you must check about SIM driver(IC connect SIM base with CPU).

I hope that helps you

this may help you http://www.retrevo.com/support/Nokia-N810-Tablets-manual/id/4357ci062/t/2/

it shald be able to and it all depends on the phone provider

contact service provider

Yes, it does. The Backflip is a GSM/GPRS/EDGEWCDMA/HSDPA phone, and, as such, requires a SIM (or USIM) card to work. For further details, check its specs here.
Just my 2 cents... Carlos

you need to openline your cellphone to use other sim

Get a new phone. or try putting it in a bowl of rice for 24 hours. But it sounds like the hardware is damaged. Sorry!

check the frequency of ur country if ur in chennai india contact tis no 09444166879
also check if ur imei no is starting wit no.1 then the vodafone network it works wit any gsm

Nokia N810 is not a phone. It is an internet tablet. You cannot insert a sim card.