Here a simple answers to your on screen home and back buttons. Since you did not learn the basics I will try and point them out to you.
There are four corners on a touch screen left, right, top & bottom. You simply swipe your finger from the outside edge of the screen inward.
From the right side of the screen swipe in and click start. One swipe and 1 tap and you are back at the main start screen.
Your other complaint the back button. All programs are not identical and programmers have two options. From the bottom of the screen swipe up with your finger and press the back arrow in the lower left corner. Otherwise, the back arrow is in the middle left of the screen border and maybe also lower left. You may see both of these. Not so complicated, ugly arrows are hidden and revealed by a simple swipe from the bottom of the screen up.
1.) Start Screen Using Touch Only. Swipe the screen form the right border of the screen in the middle and tap the start tile. DONE!!!
2.) Back Button- Swipe up with your finger from the bottom of the screen. An arrow will appear in the lower left or middle left of the screen. Tap the arrow. DONE!!!
Any of other problems or concerns. I will be happy to reveal the truth if you would like to do another post.