Translation with Hex Editor

[Meteor1]

Hi, all.
I'm a newbie with the Hex editing but I want try to make a fan translation of a game.
I found the file that contains the text and with some tests I translated some text but when I find a word, e.s "Level", I don't know how translate because the translation contains more letters than the original.
Sorry for this newbie question xD. I hope that someone can help me.

[COD3RIN]

Use hex converter google it

[Meteor1]

? I know how translate an word.
The problem is when the word translated is more that the original, E.s "Level" english, 5 char; "Livello", Italian, 7 char.
If I insert a new byte the game don't open.
I wrong something?