mov dword ptr is one of assembler commands
Type 'ASM commands' or 'asm instructions' in your searchbox. This could help you. BTW, tell me if you fiund something useful.
To view the code, you need a disassembler. Think about Ida Pro 5.2 or W32DASM
To edit exe, use Hexeditor. I use Hex Workshop.
When you find virtual address in your disassembler, it will show your hex offset at the bottom (in w32dasm) OR you can simply substract 400C00 for text segment to get the needed offset. For data segment, use 401600, for raw data - 401000
Starting with easy things is much better. This way you can ease into it faster.
Think about easier things than skill edit. You'll start faster this way.
The most iportant thing is your ultimate purpose. If you tell me what is it that you want in the end, I will have a better understanding of your motives.
My own is creating a very beautifully balanced and fun to play mod, that never gets old or starts to feel too easy. That's what I need all this asm for.