Convert Obj/DFF and other into YDR model Format

[Voltrock]

Can you explain me how to convert a model obj or DFF into YDR model?

i ve got this one : http://www.sendbox.fr/99945e85ac8f8066/hei_dt1_carrmp_deck_decals3.obj
How do get hei_dt1_carrmp_deck_decals3.ydr??

I saw one or two tutorial but it was not very clear

Thanx you very much!