The receipt that was sent to you was sent by who? maybe you can contact them for more info.

If it is by air, you will have to go towards the departures terminal.. u drive past the Airport signal as if u are going to wakra, at the signal after that you make a u-turn and enter into the secondary lane on your right. find parking and walk towards the Cargo Services...

If Seaport, which I doubt, you will have to head to the seaport..

but do you know what the items are so that you can go prepared with all the documents needed?