Hello everyone,
I am trying to apply a texture onto a polymesh (I simply go to Texture -> Upload -> Select BTM file),but while according to the tutorials Ive seeen the texture is applied authomatically, nothing happens in my case 
Do you know why’s that for and how I can fix it?
Thanks in advance
You must be looking at a really, really old tutorial from the days when a Tool could have only one texture applied. Once SubTools were introduced, ZBrush provided a way to apply textures separately to each SubTool. After importing the texture into the Texture palette you need to make sure you have the desired SubTool selected (assuming the mesh has SubTools). You then use the selector patch in the Tool >> Texture Map sub-palette to open the pop-up Texture selector.
The Tool >> Displacement Map and Tool >> Normap Map sub-palettes can be used to hold those maps as well.
To move a texture from the current SubTool back to the Texture palette (or Alpha palette for displacement maps), you use the Clone button next to the texture patch. That lets you then export the texture from ZBrush.
Also, saving a ZTL with textures applied to the SubTools will save those textures with the ZTL so that you don’t have to save them out separately.