What kind of plants are these?

I can tell by looking that that is a CO2 injected tank. Yes, CO2 systems are expensive. But they are easy.

How can I tell? All of the plants have lush growth and are bright green.

You'll learn quick that many plants go by their scientific name instead of common names.

The left corner (not the carpet) in the front is Anubias (possibly Anubias nana).

The back left corner I believe is Java Vern.

The front carpet I think is Staurogyne repens

The back middle looks like Dwarf Hair Grass.

The front right looks like possibly some kind of ludwigia, but I'm not sure. The one behind it might also be.

The back right looks like Cabomba.

Substrate:

Seachem flourite is a favorite among plant keepers. 3 inches should be good.

Lighting

Many people use T5 daylight bulbs. I would definitively upgrade your lights.

CO2:

A CO2 system will run $100+ but it is a reliable system. To grow most of these plants and to get the carpet look you'll need CO2.

Fertilizing:

I don't know much about this. I think basically you could start out with Seachem Flourish and add supplements as go when you see issues.

CO2 testing and additions:

You will want a diffuser. A drop checker is also helpful. The drop checker basically tells you when you have enough CO2 in the water. When you have enough CO2 you'll get to a pH of 6.6 .

None of those plants need a CO2 diffuser.

They are all beginner plants and really easy to keep.

What I see in the picture left back to right and front: anubias, java fern, hornwort, ludwigia, what I think is temple plant but cannot zoom in on this device to see, and Staurogyne repens.

heres the photo: