How to convert a png file to texture file (*.dds)

Hi fellas, I'm here to know how to convert a png file and make it work as a texture.
I tried with several applications (converters from png to dds) but every time I converted when I go to NBA 2KX Tool and import it, the program shows me a Java error:Java.io.FileNotFoundException
specifically, I 'm trying to edit gooeyoverlaystatic.iff file, I'm creating a Nba on tnt mod with watermark and wipe included, so anyone who can help me, could save me from hours lokking for solutions. Thanks in advance!

unfortunately the 2kx tool does not work with CF files. You need to use the 3DM Mod Tool
Tutorials on how to use it can be found in my signature