My b2evolution Version: Not Entered

Hi people! I'm trying to have different options of archive to different blogs. This is important to my site, but I wasn't able to do that. I tried to change the _main.php, but it didn't work. And I don't have a "archive.php" in my lits of templates. What can I do? My site is ht[i][/i]tp://fernandafranca.com/in/index.php? I want all the blogs to be archived post by post, but only blog 5 to be archived monthly. Is that possible? Please help me. And sorry for my english.