Place your right hand on the piano with your thumb on c and each finger on the note in front of it.
Play the notes c, e, and g at the same time. Be sure your fingers are slightly curved as this helps you press all 3 notes down at the same time.

You just played a chord!
Notice which numbers of the scale are used. 1, 3, 5
Octaves
Did you notice that 8/1 is also c? Notes 1 and 8 have the same name.
Notes that have the same name and are eight notes apart are called an octave. The prefix oct- means 8 (as in octopus or octagon). An octave can begin at any note. Example: d & d make an octave, f & f make an octave.
Play a couple C Chords with your RH and then a few with your LH. Which hand feels stronger for you? Your fingers will become stronger and be able to stretch further with practice and exercise!