but since addliquidity is payable function , i cant figure out how to send eth which are already present in contract to while calling addliquidity function

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Address.sol#L114

To call a function in another contract and to send Ether with the call, you can use the curly brackets and add a value definition, as shown here in the first example: https://docs.soliditylang.org/en/v0.7.2/control-structures.html#external-function-calls