Fuse box piggyback - where's the earth?

[st-rider]

Hi. New to the forum as just acquired 2008 b6 estate. Getting used to vw quirks.

Transferring over dash cam and wanting to piggyback from drivers side fuse box (there isn't one on passenger's side).

Searching here it seems straightforward. Already have 12 to 5v power lead ordered. However, being a newbie to vw, passats and car electrics can anyone advise where's best to put earth wire once I've spliced in the power lead?

Also after being rear ended (hence the Passat) would like to also fit rear facing dash cam. Any advice on that also appreciated.

Thanks in anticipation.

Alex