endiggo, do you mean pattern instead of texture?
If so, there are a few ways to do this. Open up or create your pattern. Edit > define pattern. The new pattern will appear in the current pattern preset (you can later save it in a new custom preset through the Preset Manager).
EITHER: Double-click on your text layer, which will open up the layer styles dialog. click on "Pattern Overlay" and choose your pattern.
OR: Either rasterize your type layer (Cntrl (Mac) or right-click (PC) on the layer and choose Rasterize) or make a selection of the type and create a new layer. Edit > Fill, Fill with Pattern, choose your pattern.
If you want to apply a non-patterned file to the type, for example a photo, select the type layer, then drag and drop the psd file into the file with the type. You should see a new layer above the type with your photo or whatever completely covering the type. Opt/Cntrl-click on the line between the type layer and the new layer; that groups them. The type will cut out the rest of the photo, and you can move the photo layer around until you see what you like.
Hope this helps...hope I understood what you want