i just started to play with the hexing part of this game.Ive tried to change the color of the ice and it seems like im doing it the right way but after i change the numbers and then hit save and fire up the game the game wont start. any suggestions?

another thing to,if i change this does the person i play online with have to change it to or is ok if im hosting?

The original game has a "checksum" routine built into it that prevents the game from running if any of the bytes have changed. You can disable it by following this thread:

http://forum.nhl94.com/index.php?/topic/109-rom-hacking-ea-genesis-games/page__view__findpost__p__89392 (see post 4 for the easiest way)

Check out the editing subforum: http://forum.nhl94.com/index.php?/forum/6-editing-hacking/

The NOSE tool lets you change the ice colour without doing hex editing. NOSE also removes the checksum for you, so I recommend running a ROM through NOSE before starting to edit it.

If you play online against someone, they need the exact same ROM as you.