hi, I am trying to calculate CO2e per activity in diferent process, but i don´t know how to calculate the emissions per Activity

For example, for the activity create the invoice i don´t know if i have to calculate the indirect emisión for this activity and how to do it, perhaps in activities like send a order, it is posible to measure the emisión for the parcel, but i don´t know which is the right way to calculate the emissions for an activity in a process.

Thanks in advance.