Here's a copy of the spreadsheet with your brew in it.
What I did:
1. Entered your water profile on Sheet (1). You don't need to come back to this sheet again now it's done.
2. Entered your grain bill on sheet (3). I changed the colour units from Lovibond in your screenshot to EBC. I also corrected where you'd entered 0.5, 0.4, 0.3 etc. in the Quantity (g) column to what I think you meant: 500g, 400g, 300g etc.
3. On the Water Adjustment (4) sheet I fiddled around with the lactic acid amount in cell B29 until the Estimated Mash pH dropped to 5.39 which is a good figure for a brown beer. I'm making the assumption here that you have a bottle of 80% lactic acid in your cupboard! I did not add minerals on that sheet because your water is really quite good already.
What you need to do:
Enter your mash and sparge water volumes in cells J17 and L17 on sheet 4 (Water Adjustment).
Now you can click on sheet 5 (Adjustment Summary) and read the amount of lactic acid to add to your mash in cell E26 (it reads 3.8 ml at the moment).