Basic Defense?

My defense in some elements like fire is very bad. how can i make it better? (sorry for my english)

 

The armor and accessories you wear have elemental defense values under their health that can be negative or positive. this is what is making you have negative fire defense. The only way to fix this is to get different armor.
Weapons can also have positive or negative elemental defense% values which can also affect your elemental defense values in a multiplicative way.

However, seriously don't worry about elemental defenses unless it's like -500
Like, you should be fine unless it's ridiculously low.

 

The popular phrase is "ele defs don't matter", which is half true: they don't matter unless they're really low, and then they really matter if you face a rapid-fire or shotgun-type enemy.