How can i do more than 1 mod with data.zip file, cause when i do another mod it over ride the last one i did

You're going to have to do them yourself. Find out what you want to incorporate from each and edit the files the way that you want them.

The only reason people provide their data.zip files is so that it's easy for you to incorporate their mods.

You can start with the wiki - you'll find some basic mods there, and doing those will familiarize yourself with how to do them. And then you'll probably be addicted and go crazy on your own... I know that I can't even drive to work anymore without thinking "What can I do to make it even BETTER?"