Adding values from one colored cell to another

Hello everyone, i am working on a Vba Project

Here Upload(1).xlsx is the demo excel file and final. xlsm is the macro enabled file

actually i have created a userform that will ask user to open excel file, extract some data from the file and do some calculations

I have some fields in userform names as firstanchor, secondanchor and so on till seventhanchor

i have a another field called risernumber which user will enter and my application will look for that particular riser number and do some calculation

now what i want is my userform to add floor-to-floor heights given in column C from firstanchor point to LightBlue colored Cell when calculate button is clicked

In my userform Red colored cell is first anchor point, green colored cell is sencond anchor point and so on (i have mentioned that in application)

I have attached a ss for reference that i want addition of that cells,

Please i need help with this asap


some parts of this project has also been posted on : OZgrid