Generally there are two ways that concrete pools are finished. A tile band along the top of the shell where the water will sit, followed by troweled quartz finish to the rest of the pool. The other is a fully tiled swimming pool, which is considered better for both looks and maintenance.
The first part of tiling a concrete shell is render. This is applied to give the shell a flat finish in which tiles can be laid, and is applied to the entire shell if you have chosen a fully tiled pool. This is not house render, it is a cement / sand mix that is able to be worked to custom suit your choice of tile. It can also be built up on steps and spas to match tile heights on walls.
The next step is tiling. The two main types of tiles for swimming pools is glass and ceramic, with glass becoming more popular of late. The tiles are manufactured on a mesh or wax sheet and sizes vary between 20mm to 58mm. The ceramic tiles are applied with a cement based adhesive however with the glass tiles, a modified adhesive with a additive will provide a strong bond to the tiles. I personally only use adhesives that are designed for use in swimming pools.
The final step is grout. With ceramic tiles it is usually a combination of either white or grey cement and fine sand. Glass tiles do allow you the option of having a basic colour palette but you should consult with your pool tiler first about which grout is best suited for your pool. If you have any further queries about pool tiling, I would be more then happy to help.