I played piano for 5 years and got up to I think a grade 4 distinction. When I first started learning the basic things I was taught were the keys (C,D,E,F,G,A,B plus the sharps and flats #/ b). Melodies are usually played with your right hand, and chords are played with your left. Learn basic right hand melodies and songs before using chords with your left hand.
When you want to progress into bringing your second hand in, practice the chords with just your left hand. A good way to practice chord changes is by timing yourself and seeing how many times you can change from one chord, to another.. Time yourself to see how quickly and how many times you can change in 1 minute. You will eventually get quicker.
Once you've learnt the basic chords, or chords for the song you are learning... And you've taught yourself and become fluent using those chords, you can then progress to using right hand and left hand at the same time. This will be very, very confusing at first as the left hand is different from the right hand in most songs. If you are learning basic songs such as Mary had a little lamb, Jingle Bells, etc it will be much easier to learn both hands at once as the chords are pressed when the right hand is playing a note, so it's more in sync. Whereas songs like "Rivers flow in you" by Yiruma are much more complicated as the chords are pressed out of sync with the right hand.
YouTube tutorials can be helpful as well if you need extra help