Hey Susan, not sure where you're taking off from, but if you can try beaching your board. That's how I usually start when I take my Black Lab out. This way he can just walk onto the board and I'll have him sit. Then I'll push off and hop on. You may also want to try paddling on your knees until you both are comfortable on the board together.
It took a time or two until we were both able to stand up together, but once you guys are both comfortable you'll have a great time together.