Hello.
I am very new with Altium Designer ( coming from Eagle ), but on the 1st try I've stuck.
I've checked the documentations online, and everything pointed that the pads should be located in Schematic edition in Place->Pad, but there is just not such an option.
Perhaps you are not using the correct terminology to describe what you want. Pads are on the PCB scope, not schematic - unless you`re attempting to assign existing pads of component to some specific fottprint.