OpenERP views are designed and maintained in XML (Extensible Markup Language). A basic understanding of XML will help you customize views, modify search criteria, and manage workflows. Here is a list of XML resources:
The World Wide Web Consortium XML resource page is http://www.w3.org/XML/
XML tutorials and documentation are available at http://www.w3schools.com/xml/
RML (Report Markup Language) is a specialized XML format utilized for reporting. OpenERP uses RML for most forms and simple reports inside OpenERP. Understanding RML basics will help you design reports or modify headers and footers of reports. You can find a lot more in detail at http://www.reportlab.com/docs/rml-for-idiots.pdf.