Hi salil,
do you know how a voltage opamp is used as an (inverting) integrator?
You can use the same principle (feedback capacitor) for OTA`s also.
However, the transfer function looks a bit more complicated (it contains the finite transconductance gm of the OTA).
More than that, there is a disturbing constant term, which however can be kept small for proper design.
But note that you need an output buffer (unity gain amplifier).
Conceptually, all you need to do is load the OTA with a capacitor to make an integrator. If the OTA is very low gain, this could work, but open-loop signal processing is an advanced topic. In practice you should use negative feedback like as if you were using an op amp. You only need an output stage if you're driving a resistive load.