Elements aren't really all that important to know at the start, but it'll really help to understand them for constructs as well as generally for anything eventually... Elements even though many claim it, are not just programmed energy...
Elements in the simplist manner of speaking each have inherent traits and effects that can simply not be removed. Technically speaking, they can be programmed to match another element in a way, but the trait will always be present still, so for programming energy to be like a different element, it is best to use ambient energy.
Knowing each element allows your constructs to function better in terms of letting you make sure the traits and such align properly with the construct's purpose itself, of course, you won't always be able to get the "best element" for the function buuuut... Ambient energy will usually work best in that case.
Every energy system has inherent elements that are present inside the system, of course, it's possible to get elements added to your system through multiple methods... One is through a deity, and technically, through aritficial means such as a construct that gathers some of that element... Everyone can use a small bit of each element, which is how the artificial method is possible, and something I have seen many do in the past.
Albeit, the thing that decides the element energy is, I have yet to figure out.
The known elements are...
Void
Chaos
Cosmic
Solar, Lunar
Death, Life, Time
Light, Dark
Fire, Water, Earth, Air
There are obviously more, it is irrational to believe otherwise considering all the different "materials" in existence, but these are the only ones I know of.
Though, each element does have different states, freezing water = ice, etc... As well as storm existing, which, I dunno, there are some people that have it naturally, but generally, it's just combining elements to get it, etc.