(1) Turn ON hidden geometry. (View menu)
(2) Soften/Smooth the curved surface first using the Eraser Tool with the CTRL key modifier, on the hidden lines.
(Pay attention to the statusbar. It will tell you what the options for each tool is.)
There are other threads here that covers this nicely.
Help Using Textures on Cylindrical Objects
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[url]Search results for 'curved surface texture[/url]' - SketchUp Community