[XeTeX] ArabXeTex: XeTeX or XeLaTex?

[@@]

Hi,
Ooops my previous post was more incomprehensible!

I began to discover latex and I have two problems with this ArabXeteX file:

\documentclass{article}
\usepackage{arabxetex}
\begin{document} \LARGE
This is some text in English with Arabic insertion \textarab{`arabI}.
Comme quoi \c{c}a marche !
This is some text in English with Arabic insertion
\textarab[utf]{عربي}.Texte UTF non vocalis\'e !
This is some text in English with Arabic insertion
\textarab[voc]{`arabI}.Texte vocalis\'e !
\begin{arab}\LARGE
bism al-lahi al-ra.hmani al-ra.hIm
\end{arab}
\begin{arab}
wa-ha_dihi fiqraT"uN bi-al-`arabiyaT ma`a kalimaT inklIziyaT.
\end{arab}
\begin{arab}[utf]
وهذه فقرةٌ بالعربية مع كلمة انكليزية.
\end{arab}
\begin{arab}
wa-ha_dihi fiqraT"uN bi-al-`arabiyaT ma`a kalimaT inklIziyaT
(\textroman{English}).
\end{arab}
\end{document}
1) When I try to compile it as a file XeTeX, I have the following error:
Undefined control sequence: \documentclass{article}
2) When I try to compile it as a file XeLaTeX, the command \texroman
does not work:

! Undefined control sequence.
l.24 ...abiyaT ma`a kalimaT inklIziyaT (\textroman
                                                  {English}).
?
[1
And in the pdf output the word English is written in Arabic.
Without this command the file is compiled correctly.
Any help?
Regards
P.-S : Monsieur F. Charette, si vous me lisez, vous pourriez m'écrire
en privé (mon anglais est loin d'être parfait). Merci.