For using Weeks from today Follow these steps.
1-Enter the number of weeks in the first input fields
2-Select the time frame in weeks condition put just keep it default
3-Choose weeks you want to calculate from now in the future or past( select from for future and before for the past)
4-Select the date from which you want to calculate
5-Tap on calculate button .
6-Congratulations! you have successfully calculated your time frame.
Note: Current day and date showing is calculations from current date.