documentclass[a4paper,12pt]{article}
usepackage{fontspec}
usepackage{fullpage}
setmainfont{MyFont}
begin{document}
Hello world hello world Hello world hello world Hello world hello world Hello world hello worldHello world hello world Hello world hello worldHello world hello worldHello world hello world Hello world hello world Hello world hello world Hello world hello world Hello world hello world.
end{document}