Help-climber has outgrown trellis!

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Any idea what I should be doing with this? It's a Blue Solanum (Solanum Crispum Glasnevin).

The idea was that it would cover the trellis nice and thickly and hide the shed from view. But all that has happened is that the bottom half is bare if leaves and the rest of it is aiming for the sky!

I probably should have pruned it but I had no idea where to start. And if I cut it back to the height of the trellis it's going to lose most of its leaves and potential flowers. I also read that pruning should only happen at very specific times of year. Any idea how I can salvage this?

To clarify, the trellis but is supposed to be growing on is the one parallel to the front of the shed. The trellis on the side is just the fence that my neighbour put up.

Another picture, it's hard to get it clear.

Prune after flowering.

see if you can bend stems horizontally and fix them to the trellis

Thanks!