> how do i know how much is left for the program to 
> download untill it finishes downloading? 

You can't, because there is no way to "know" how many 
links or files do exist in a website. HTTP is really 
different from filesystem-oriented protocols, such as 
ftp

For example, when you mirror a complete ftp structure 
with a ftp client, you can ask the server "tell me how 
many files are in this directory, and what amount of 
data it represent". 

With HTTP (used for WWW), you just can't, the only 
thing you can do is to request a page or a link you 
know from its URL, and then scan it to extract all 
links if the file is an hypertext document (HTML), and 
then download collected links, scan them and so on.. 
until the last page, you can't know how many links 
will remains.