How do I turn the material of an object white?

buttercupsaiyajin_b3ffb4c8a4

Daz Studio 4.9 doesn't seem to have a Material room like Poser.

sriesch

The Surfaces pane has the various parameters that control materials. 

If all you want to do is make the material white, you would typically set the Diffuse color to white, and click any thumbnail image in the diffuse and set it to none.  Of course, there are many other parameters that affect color as well, there could be ambient, reflection, bump, displacement, etc. or even a custom shader that uses different parameters. 

If you had a specific shader (or shader preset) you wanted to apply, you would select the surface, then in the content library double-click on the content thumbnail for that shader/preset.  Depending on the shader, you may need to apply the shader first (some presets also apply the shader at the same time, some do not and thus you will only get some properties adjusted without it being fully functional.)

Some shaders make use of the shader mixer pane, which allows you to create/modify shaders.