Xemectrum

I need ASM tutorials urgently......And I have some questions:

1) When we MOV the value of the address to a register, WHAT register`s value will be copied??
example: MOV EAX, [00100000]. What register of 00100000(address) will be copied into EAX?????

2) If I want to copy the ECX register of Address A (e.g. 00100000) to EAX of Address B (e.g. 00200000) , WHAT should I do???? (Cheat engine AA script)

3) If I want to change an address`s opcode (or bytes) with a condition, what should I do??? (Cheat Engne AA Script)
Example:

cmp eax, 100
je ABCD
jne EFGH

ABCD:
** Change opcode/byte of 00100000 to push eax (hack)

EFGH:
** Change opcode/byte of 00100000 to pop eax (original)

1) mov eax,[00100000] = move the value inside address 001000000 into register eax