You will need to convert the powerpoint to a one page document in Word.

Use Zamzar to convert from ppt to docx : http://www.zamzar.com/convert/ppt-to-docx/

Once converted , Install this to your WordPress Site

https://wordpress.org/plugins/mammoth-docx-converter/

Once activated, go to Add Post , scroll to the bottom of the post and you should see: 

Find your .docx document and upload it , then click insert into Editor