Three things we look at when trying to grow plants in an aquarium. 1 is the amount of light in your tank 2 the type of substrate you are using like sand or gravel or dirt and 3 if u want to use c02 or not. There are some plants that need more of one than the other of course but as you are a beginner I would just suggest starter plants like anubius, java ferns, crypts, and amazon swords even moss. Also underwater plants reproduce differently than normal. Most don't use seed like normal plant but instead grow their own baby plant from its root and place it right next to it or grow a stem and have baby plants grow on it like amazon swords. Stem plants can be cut in half and simply replanted and bam! I just like the that you have two of them like ludwigia repens.