Waterfall play set - Help, can't work out how to set up the plumbing!

[SnowCastle]

I am in the process of a mega play set sort out and have now reached my UK Waterfall but I can not for the life of me work out how to connect the tubes up. It may be that I am missing a bit which is why I can not work it out or I am missing something obvious?

If anyone can advise or even better show pictures of the underneath and back it would be very appreciated!

Thanks!

Cat x

[Mirnyj]

I don't have that playset unfortunately, hope someone can help!