Yappe

I heard tiger barbs need a planted tank.
-How many plants?
-Should i lightly plant it or heavy?
-Should i lightly/heavly plant one area? or scatter?

Barbrella

You can put plants on the sides of the tank and in corners. You must keep a large area open for swimming but tiger barbs spawn in plants so do need some.

Gunnie

You can plant your tank any way you like, but like Barbrella said, your barbs will need an open area for swimming. I usually put my plants in the back of the tank, and leave the front wide open. Here's a really good article to help you out some:

http://plantgeek.net/article_viewer.php?id=17

Plantgeek also has a great plant guide section which will help you determine which plants you want in your tank, and where they are usually placed in the tank:

http://plantgeek.net/article_viewer.php?id=17