Write back sales prediction in Power BI with Power apps

[MarieKatherineJ]

Hi community! 

I would like to write back in PowerBI. The goal is to predict sales for each month in the next year, and visualise its effect on future inventory, margin, etc.

I understand a little bit how Power Apps works with Power Bi. I was abble to create a little app to enter comments on a list of product. However, it seems like the sales prediction is a little bit more complex than that.

The data to write back would be sales prediction for every month of the year, and filtered by category. 

Example :

For my category Sofa, in my subcategory Modular, I would like to enter a sale prediction of 150 000$ in January 2024, 200 000$ in February 2024, etc...

In my subcategory Futon, I would like to enter a sale prediction of 50 000$ in January 2024, 70 000$ in February 2024, etc...

Note : I have already created the table in PowerApps ( "SalesPrediction").

I would like to create an App in PowerApp that would look like this : 

And this app would need to fill a data table like this  (note that I have already created this table in PowerApps) :

Can you please help me! Basically I struggle with the creation of the app and to write the right function/formula in PowerApp.

Thank you