Two party payment channels, how to set one up? Most guides to LN describe it working "through 'payment-channels', wherein two parties commit funds", usually Alice and Bob. But I cannot see a way to actually create this scenario. I've just started running my own lnd node and I can open, and fund, channels to other peers, but this always seems to be a single fund of the channel.
As I say, I've just started out in the LN world so I may have missed something blindingly obvious, but how does one go about funding a channel with my friend Bob?
what you are talking about is usually refered to as dual funded channels. This is a feature that did not make it into the current version of the Protocol (BOLT1.0). However it was agreed by the developers that it should become part of BOLT 1.1. Currenly C-lightning has most progress towards this feature. 

There is a legacy feature push_msat which opens the channel from one side but allow you to already push funds to your friend. however you should not that these funds lost directly. 

If you want to be able to receive funds on the Lightning network there are three options: 
1. someone else opens  a channel withyou (for example when they want to send you money anyway)
2. You pay someone on the lightning network or buy something after you have opened channels
3. You use an onchain / off chain swapping service after you opened a channel but this puts requires and additional on chain transaction.