Capturing download capacity

I think the thing that is confusing is the word capacity. The word implies the future; in other words, what is the capacity for downloading in the future. You are saying you need to know how much has been downloaded in the past, so that makes the question confusing. I think it is often difficult to understand how to use English words (and probably words of other languages) that indicate the proper "tense" (verbs that express time).

So do you need to determine the maximum values for certain things such as the maximum speed of a download that have occured in the past to predict the capacity for the future?

what i mean is..
i need to keep track of all kind of downloads (not the links, page name or downloaded file names) while we are browsing the net. for example i need to know how many KB has downloaded when i loaded this c# corner home page. like wise i need to keep all the downloaded capacity for all the pages that i visit. how can i do this using c sharp.