Create a save data normally. Then copy it to your memory card by going to the left option in the Wii Menu.
Hope it helps.
If you need a specific tutorial for it, PM me.
Hi, I had a question about using a memory card for the Wii fit plus program. If I use a memory card will my settings be saved on the card if I go to another person's Wii and use their Wii fit plus? Also will any memory card work?