So, that makes more sense, now! I bet you now found information online about the E373, right?
While still a fairly basic keyboard, it does have some nice features for its price, including the S.Art Lite voices, as well all of the DSP effects included with it.
If by "3 keyed notes", you mean regular 3 note chords, then that is a very good idea. While the easy-play features are nice to get started, and useful for someone who just wants to make music on a particular keyboard, if you learn how to play the proper notes of chords, then that gets you on your way to being able to play any keyboard, not just a particular model or those of a particular brand.
I would start with learning the basic 3-note chords -- major, minor, diminished, augmented, and maybe suspension-4 -- for all notes/roots. In other words, learn those chords for C, C# (or Db -- same notes with different names), D, Eb, E, F... etc. -- all the way to B. Then, learn their inversions. For example, a C major chord in root position is C-E-G, but you also want to get used to playing it as E-G-C and G-C-E for a couple reasons. First of all, it often makes it easier to switch from one chord to another when you know the different inversions. And secondly, sometimes a song will call for a particular note to be the lowest note played in the chord at a particular time.
And then, or at the same time, start learning the basic 4-note chords, such as the 7th chords, minor-7th chords, diminished-7th chords, and 7-suspension-4 chords, along with their inversions.
This sounds like a lot, but as you just play songs, and get used to playing the chords, you just naturally learn them. And while you may want to start with songs in easier keys (such as C, G, and F -- key signatures with few or no black keys), as you get used to playing, don't be afraid to learn songs with more complex key signatures, with more black keys in them. Learning the scales for these different key signatures helps you learn what black keys are in any given key signatures.
Feel free to ask us here if you have any questions!