I mean, i noticed that lot of imports that can be included in the game are just images ( like, when i want to download hair import i found only an image of the hair and not an SWF file ), or code.
My question is : how can I load this imports in the game?
We have a little bit of a language barrier here I think, but if I understand your question correctly you're asking why some parts of a mod don't appear sometimes?
My guess would be that you're not using the Loader. It's required for some mods.
I can recommend downloading sby loaderpack. It expands the game and enables all sorts of cool stuff that doesn't work with just SDT. If you are already using the Loader then I can't answer without knowing more.