I think you may have to create an output data set and send the results to a graphing procedure such as SGPLOT to have more control.
The message you got about "contents of the attachment doesn't match its file type" means that you may have done something to mismatch things.
If you generate output in the text output window then 1) copy the text from the output window and in the forum open a code box by clicking on the {I} icon and paste text into the opened box.
Images you should be able to post by clicking the 'Photos' icon , navigating to wherever the output you create resides and dragging or selecting the image file created, hopefully a PNG file.
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