Can someone explain a external Wastegate?

Basically I did not understand why it has two inlets? I know one goes to the manifold but where does the other hole go to? I interested in upgrading my manifold to have an external wastegate and I am not sure of how to install it.

A wastegate is a bypass used to control the amount of increase offered by the turbocharger. Since the turbo is driven by the exhaust gases leaving the motor, varying the amount of exhaust passing through the turbo will differ the amount of increase the turbo is making. The opening of the wastegate is attached to the exhaust manifold upstream of the turbo, and the outlet is attached to the exhaust downstream of te turbo. When the computer needs to decrease the amount of increase, it opens the wastegate, typically using a vacuum line controlled by a solenoid so that the exhaust gases bypass the turbo, decreasing its speed, and lowering increase. When the wastegate is closed, the exhaust gases have to flow through the turbo, speeding it up. An external wastegate means that it's a separate part from the turbocharger itself though they're typically mounted beside each other, and this is different from an integral wastegate, which is really part of the turbo housing itself.

Good answer Harry nothing to add