How do I put tiles on a liner for fish pond?

See if these help you.

https://youtu.be/ibszRBO-CeQ

https://homeguides.sfgate.com/edging-goes-around-ponds-42160.html

https://www.velda.com/ponds/build-construction/edging/

You could put tile or I would even recommend decorative river rock.

I would lay concrete over and under the rubber edge and smooth to lay your tile onto using mastic when concrete is dry..

You don't. Stone, pavers, or wood. To hold the liner from falling in or folding.

When I built my pond, over 8 years ago, the instructions were to build a berm above the waterline and lay the liner on that slight grade - this helps to keep water in the pond in the event of a lot of rain or accidental overfill. It also keeps unwanted chemicals from spilling into the pond - again in the event of flooding. That said, the back side of the berm was filled in with rock (for drainage) and then whatever slate or tiles you wanted were set on that - overhanging the waterline. They were not cemented in, just put there so you could move them if necessary. Like I said, my pond is 8+ years. The foliage has grown over and everything looks quite natural and lovely.

On a side note: Lime will alter the PH value of the water making it deadly for the fish. It is also a problem that will not go away so the best way to cure it is to treat all new cement work with a neutralizing agent, carefully following the manufacturers instructions, or paint the cement with a special pool paint to cover it. "Homework" is essential.