For version 3.7.0 please see the steps below
First select Add Exercise on the Diary tab
Then choose 'Create Exercise'
Then choose : 'Value Estimator'
Now just enter your calories and you get an exercise value
For older versions :
First select Add Exercise on the Diary tab
Next Choose the Value Estimator option
Now just enter your calories and you get an exercise value
Remember to redisplay helpful hints to learn what all the buttons do see this FAQ