[otrs] adding an java script applet to header.dtl

dear all my professional friends i wanna add an java script and css to my header.dtl file to see that in my all default header. .. when i saw to header.dtl i found the following code which i guess that i can use css only please guide me to solve that... # include css file <title>$Config{"ProductName"} $QData{"TitleArea"}</title>