XML : from DTD to XML schema

I have this DTD:

  <!DOCTYPE a [    <!ELEMENT a (b?, c*, (d|e)+)>    <!ELEMENT b (#PCDATA)>    <!ELEMENT c (#PCDATA)>    <!ELEMENT d (#PCDATA)>    <!ELEMENT e EMPTY>    <!ATTLIST c attr CDATA #IMPLIED>  ]>    

I want to convert(manually not by program) it in Xml schema, but I don't understand how do I create attribute for c element.