Hammond 27969P Metal Box
Connecting to the BNC. The SBT-11A has five connections, two are ground the other three pins are the anodes. There are actually four in this tube, the centre of the three pins connects to anodes 2 & 3. The outer two connect to anodes 1 and 4. So these should be connected in parallel.
Attaching the selfie stick. This is a cheap Chinese stick from Ebay, it's telescopic and can extend to about 1 meter.