Getting Errors While Running Tic Tac Toe App After Writing Codes

I’m Getting Multiples Error after Writing The Code.
Few Of Them Are :-
1: Expecting member declaration
2 Expecting an element
3. Unexpected tokens (use ‘;’ to separate expressions on the same line)
4. Expecting ‘)’
5. Unresolved reference: View
6. Unresolved reference: button7 (BUTTONS)
7. Unsupported [Collection literals outside of annotations]
8. Unresolved reference: updateValue
9. Unresolved reference: PLAYER
and many more, I Understand Its Impossible For One Person To Solve My Issue But Please Try To Solve Atleast One Query, I Write All The Codes As Same As Video But I Don’t Know How They Getting References and Funcation After Press 2-3 Keys. Thanks In Advance