Jack's method works well. Or, you can be a "real" canoeist and do your solo thing without using a seat.
YOu did not say, but I presume the canoe has thwarts and/or a carrying yoke/thwart. What you can do is simply take up a kneeling position amidships of one of the thwarts with your butt or lower back snugged back against it and paddle away. YOu'll be a bit lower in the canoe than in a seat and probably a bit more stable.
Hawkeye