Hello
You need to perform two requests:
Firstly, you need to create your document:
POST http://localhost/7/rest/content/site/CorporateSite/en-us/document/Extras2 HTTP/1.1
User-Agent: Fiddler
Authorization: Basic YWRtaW5pc3RyYXRvcjo=
Host: localhost
Content-Type: text\xml
Content-Length: 151
<CMS_MenuItem><NodeClassID>3470</NodeClassID><DocumentName>aaaRestTest</DocumentName><DocumentPageTemplateID>79</DocumentPageTemplateID></CMS_MenuItem>
This will return the DocumentID needed for next step.
Then you need to create the attachment:
POST http://localhost/7/rest/cms.attachment HTTP/1.1
User-Agent: Fiddler
Authorization: Basic YWRtaW5pc3RyYXRvcjo=
Host: localhost
Content-Type: text\xml
Content-Length: 3305
<data>
<cms_attachment>
<AttachmentMimeType>image/png</AttachmentMimeType>
<AttachmentSize>2110</AttachmentSize>
<AttachmentExtension>.png</AttachmentExtension>
<AttachmentName>TestAttachment.png</AttachmentName>
<AttachmentDocumentID>694</AttachmentDocumentID>
<AttachmentIsUnsorted>True</AttachmentIsUnsorted>
<AttachmentImageWidth>32</AttachmentImageWidth>
<AttachmentImageHeight>32</AttachmentImageHeight>
<AttachmentBinary>
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
</AttachmentBinary>
</cms_attachment>
</data>
David