Hi and welcome to the forum! There are lots of folks here that can help you at all stages of growing. I, myself, am a new guy also on my first grow and the people here are amazing. From what it looks like, your first leaves, or cotyledons are turning yellow. The second set look ok. If I’m correct, this is normal, as the first leaves provide nutrients to the seedling until its true leaves unfurl and begin the process of photosynthesis.
Some of the pros will be along to help with the issue.
Keep an eye on your watering, though. I only mist the soil a few times a day and my babies are doing fine. First rule of growing, don’t overwater. You can love your girls too much.