To cite an exhibit or page in HistoryWiz you may use:

For an exhibit:

Brainard, Jennifer. "Title of page." Name of Exhibit. Oak Harbor: HistoryWiz/ 2008. Your date of access. <http://www.historywiz.org/nameofpage.htm>

For a page:

Author, First Name. "Title of Page". Date of last update. Supporting organization. Date you found the site. URL

Brainard, Jennifer. Title of page. 2008. HistoryWiz. Your date of access. <http://www.historywiz.org/nameofpage.htm>

If you are a student, of course you should check with your teacher or instructor for the preferred form. MLA is not the only citation form.