First time trying seedlings at home, I’m killing them - help!

looks like your light source is to far away from the seedlings. I give my grow lights about 4 inches above the plants. If you don’t have a grow bulb light...it mimics the sun, you can use 1 bright daylight light bulb with one that has a more yellow tones to make the full spectrum. keep raising the light as the plants grow.

Correct amount/combination of water, soil, and sunlight. Too much or too little can kill them. And the correct amount varies depending on the kind of plant

Maybe try covering them with a plastic to create a greenhouse affect?

https://thefreerangelife.com/common-seed-starting-problems-fix/

Cindy, you beat me to it. They look really dry to me. I would take a pan and put a layer of small rocks in the bottom and then put your seedlings on top of the gravel and then cover with plastic. Water your seedlings from the top and make sure that they aren't sitting in the water, Good luck with your plants,

Start by replanting without the small carton around the plant. It's trying to grow but can't. Roots are being strangled. Spread the plants out. Certain plants need more water, some need less. The same with the sun and shade.

My guess is you have more than on problem. Yes, you may need to water more, the container "pots" look dry. Add water, not too much. The plants need to be moist, but not dripping wet. The plants will effectively drown if they have too much water (depending on the type of plant). But I would also say you need more light. Your plants look leggy. If you are using a light (grow light or whatever) put it closer to the plants and maybe leave it on for longer. You may not have enough light - the light should give good coverage to all the seedlings. If seedlings are bending toward the light, not growing straight up, you need more lights. If you can, depending on weather conditions, put the seedlings outside to get more light.

I use The Old Farmers Almanac to help me (almanac.com). I also grow my garden from seed so I know how temperamental seeds can be. Good luck.

You need a really good light source that starts close to the plants then you raise as they grow, otherwise they are always reaching for the "sun" and grow spindly. Also a slight breeze make the stems grow sturdier so you could put a fan on then periodically (Distant, you don't want to blow them over).

the light being too far away means they get lanky stems. But you need a product called No Damp to add into your watering can to prevent them from "damping off." That kills the seedlings.

I too think you need more light, if you have a South or east facing windows put them on your windowsills. Turn the trays whenever the flowers bend towards the window, this will help them to grow strong! Water seeds once a day, when seedlings emerge water twice a week depending on the flower (Never over water)! Oh & Start over you still have time, btw egg cartons fit perfectly on a windowsill put your dirt and seed right in them! Good luck! ;-)