The online web site would have to support cut and paste and it's very unlikely that any text formatting in the document will appear as intended. If that's acceptable to you, type the resume in Notepad and do the following:
1) Right click on the text and click "Select All."
2) Right Click again and click "Copy"
3) in the online text box, right click and select, "Paste."
Notepad produces only the text so there will be no formatting problems. It will also help if you turn Format/Word Wrap off in Notepad before doing the above. That will allow the on site text box to format the text to it's own settings.