That's more or a modelling question, but let me give it a go. I'm not really an experienced modeller though xD
If you got a model in Maya, you can navigate to the lambert1 material which should already be assigned to it. Open the Attribute Editor on the right side of the screen and go all the way to the right of the list. You might be able to get right there by holding right click on the model (in object mode) and assigning existing material > lambert1. Once there, click the color option which takes you to a new window where you select "File" then locate your texture file (use .dds) using the browse button on the color panel. Once loaded, it's up to you to actually map the texture, something I am not the guy to explain to you how.
Perhaps this source can be of assistance:
http://www.creativebloq.com/3d/how-textu...-121310050