Hi memoe madi, welcome to Beemaster!
As Jim mentioned, that first picture looks like nectar and pollen to me. The picture is a little small to see clearly (the file size limit here is frustrating, I know), but I think the darker stuff in the cells is either pollen or a darker-colored nectar. The nectar will off course be liquid, and pollen will be sort of a chalky substance that the bees have packed into the cells, and both the nectar and pollen come in a variety of colors depending on the flowers the bees are visiting.
I believe I do see eggs in that small piece of white comb, which confirms you have a laying queen. But, if like Jim mentioned, your queen is newly laying, you may not see much hatched brood or any capped brood yet. It takes 3 days for the eggs to hatch. After they do, the larvae, which look like little bright white grubs who sit in the cells in a C-shape, will grow until they fill up the cell, which will take about a week. At that point the workers will cap them over with wax so they can pupate and turn into adult bees.
I know it's hard when you first get bees, but try not to inspect them too much, no more than once a week. They need time to work and get the colony built up, and every time you open them up, they have an interruption to their work.
I also just noticed something else, taking a closer look at your pictures. You will want to remove that extra piece of rogue comb that has been drawn on that frame. Bees will maintain a 9mm gap between their combs, we call this "bee space", which means that every comb they draw next to this frame will continue to be crooked all the way down the line. Off-center or cross-connected combs will make inspections difficult and lead you to damage the comb every time you pull the frame, so best to correct this now, while they are in a drawing mood.
Good luck with your new girls, and keep on asking any questions you have. We are happy to answer them!