So I am making a Boston Celtics Theme for my friend ( Yeah I know

how long has it been since I last did this

)
So anyway I working on the theme and I started to use the Transformers theme as a base. I was able to extract the board.ash file succesfully with one of leathl's apps...it turns out ash.exe ( Aether's GUI Version ) says thats its not a ash file and to try it with u8mii. So I did and it worked lol. But here is the thing... When useing u8mii to pack the file back again, should I use which heading type and should I use Lz77 compression?
Thanks in advance
P.S. Sorry for the noobieness people

I haven't made a theme or a channel in a long time so I fogot how exacly...