Yes you are right happyrabbit .
You can't really write your name "Javier" without modifications in Chinese. You will need to transliterate it and modify the pronunciation.
The 'sound' in "Ja" doesn't exist in Chinese , so you might have to make it a "ka" and "vier" ( the 'V' doesn't exist). You could make it a "bie" ,so your name would be in pinyin " ka bie" and in Characters possibly :
卡别 *kabie2*( where 卡 and 别 do have meanings separately but together are used only to sound like your name and have no meaning in that case) .
I think a Chinese native will be better helping you here.