Start at the edge of the dock under the flight path - you can use the runway lights. Along the edge of the dock there are lights with a ten letter word on the back. With A=1, B=2, C=3, etc. then the final coordinates can be calculated using the letters of that word:
N 51 30.(2nd - 8th)(6th + 7th)
E 000 02.(3rd + 5th)(1st + 10th)
A number of things to see near the start. If you come at the right time of day/week you can start with aircraft at low altitude overhead. There's also the meeting of Royal Victoria and Royal Albert Docks - once industrial now only used for leisure and occasional visits of larger craft to ExCeL. There is a good view of Excel from here including the newer International Conference Centre and further to Canary Wharf. The Connaught Tunnel passes a little to the east. The tunnel formed part of the North London Line until 2006 and will (eventually!) become part of the route for Crossrail.
Also views of old and new: to the east, you can also see Building 1000 - now home to a large section of Newham Council - as well as space for the rest of the Royals Business Park. In the other direction you can see the derelict Spillers Millennium Mill - there have been a number of plans for redevelopment since I've known this site but it seems only a little preparatory work has actually happened. There are many documented visits from urban explorers worth a look if you like that sort of thing. For a more 'official' version see for example lookup.london/millennium-mills
The final is located on one of the more green examples of the type of structure I've seen. Previously more centrally over to mirror the start but changes made that no longer feasible. Container is (since 18/09/2021) a film cannister. Previously a 'small'.