public void execute(final Request tilesRequest, final AttributeContext attributeContext)
throws PreparerException {
    attributeContext.putAttribute("myAttribute", new Attribute("hello"));  //For starters put a simple string
}

<tiles:insertAttribute name="myAttribute"/>

<definition name="template.main" template="/WEB-INF/jsp/templates/templateMain.jsp"
preparer="com.ernyz.vacation.web.ViewPreparers.HeaderViewPreparer">
    <put-attribute name="header" value="/WEB-INF/jsp/components/header.jsp" />
    <put-attribute name="footer" value="/WEB-INF/jsp/components/footer.jsp" />
</definition>

<definition name="login" extends="template.main">
    <put-attribute name="header" value="/WEB-INF/jsp/login/loginPageHeader.jsp" />
    <put-attribute name="content" value="/WEB-INF/jsp/login/login.jsp" />

</definition>

<definition name="*" extends="template.main" preparer="com.ernyz.vacation.web.ViewPreparers.HeaderViewPreparer">
    <put-attribute name="header" value="/WEB-INF/jsp/components/header.jsp" />
    <put-attribute name="content" value="/WEB-INF/jsp/content/{1}.jsp" />
</definition>

<definition name="*/*" extends="template.main">
    <put-attribute name="header" value="/WEB-INF/jsp/components/header.jsp" />
    <put-attribute name="content" value="/WEB-INF/jsp/content/{1}/{2}.jsp" />
</definition>