Go to the top of the entry page and it will say previous day. Before you go there, delete what was put in the wrong place by clicking the appropriate red "X" to the right of the entry that you want to delete. One that is done, you can go to the previous page and enter it in. You can enter it first in the proper day and then delete. It really doesn't matter.
Fitday St Date (this time): 5/20/10/Actual: 1/1/09
St Weight: 252lbs/283.5lbs
Current Weight: 241lbs
Total weight lost: 11lbs
Goal Weight: 142lbs
Goal Date: Just taking each day at a time.
Mindset: "Never go back into the 250's!"