Like almost all models of phones, you slide off the back cover to install the battery.
To install the battery you must first remove the back cover, which can be tricky. Here's how I do it:
0) wash & dry hands (greasy skin will slip).
1) turn over phone so the camera lens is facing me
2) hold the phone in my right hand and put my right thumb firmly in the middle of the back cover
3) put my left middle finger on the top of the phone (on the phone's front edge, not touching the back cover)
4) put my left thumb on the bottom edge of the back cover, just underneath the triangle/arrow symbol
5) push upwards with both thumbs while pushing down with my left middle finger.
It takes a fair amount of pressure (similar to opening a drink can). You want to hear a click and feel it move upward by about 1.5 - 2 millimeters then you can lift off the cover.
This question has been asked and answered many times previously (try searching for "battery"), if you have more questions please try the Q&A search first, the answer is probably here already & it will save your time.
answered 3 years, 4 months ago