Finally, now that your dragonfruit seeds are all snug in their protective layer of perlite / tezontle with the nutrient rich soil mix underneath ready to supply the new dragonfruit seedlings with their first nutrients, you are ready to give them the green light to grow!
Gently (you don't want to make the dragonfruit seed tray sodden or to pack down the top layer of perlite / tezontle which has the seeds in it) mist the tray to moisten the dragonfruit seeds and penetrate into the soil mixture layer - but not saturating or making the tray sodden.
If you are in a tropical climate where the temperatures are warm and the humidity is high, you can probably place your dragonfruit seed trays outside. If you do, keep them out of the direct sun (which can make the tray too hot and quickly dry it out) and out of wind and weather (for obvious reasons!). You may want to cover them to keep birds and animals away (use a screen to keep air flow and temperature levels ambient). Keep an eye out for any problems with your outdoor setup - be particularly careful about unexpected rains which can wash away your whole tray of planted dragon fruit seeds!
If you are growing in a greenhouse or indoors, you can loosely cover the tray with plastic (to keep the humidity level high). Again, keep out of direct sunlight. If your greenhouse is kept at a high humidity, you don't need to cover at all.
Now, keeping an eye that the tray does not dry out (if it does begin to dry out gently mist it again with water), wait for the seeds to sprout. This should be a matter of days not weeks depending upon the conditions of your individual setup (temperature, exact humidity, depth of the dragonfruit seed covering layer etc.). Remember to always err on the side of too little water rather than too much for the dragon fruit cactus plant.
Now that your dragonfruit seeds have sprouted, you need to care for the dragonfruit seedlings.