Most contractors would agree that putting wallpaper over ceramic tile is not the best option for re-covering a wall. However, you may find that the process of removing the tile, grout and adhesive is too impractical and time consuming. If this is the case, there are ways you can effectively apply wallpaper on top of ceramic tile with moderately good results. Keep in mind the results will not be as good as removing the tile and starting from scratch, but it can work in a pinch.
Sand the surface of the ceramic tile to remove the glossy finish that may cover the tile. Use high-grit sandpaper, 200 to 400 grain, and an electric belt sander to get larger surface areas done faster.
Rinse the surface of the wall after sanding with an all-purpose cleaner. Use a deglossing solution with a powerful degreaser to remove any slick spots from the tile. Rinse with plenty of clean water and allow adequate time to dry.
Fill in the grooves of the ceramic tile using spackle or joint compound and a putty knife. Work to keep the surface as even as possible. Allow to dry and sand rough spots that need it.
Apply a layer of bridging material or heavy-duty lining paper over the now smooth, sanded ceramic tile. This layer will provide a blank slate on which you can hang wallpaper. You may want to apply a prep coat to the ceramic tile before hanging the lining paper, but it should stick if you've adequately prepared the surface. Use a heavy-duty adhesive to hang the lining paper.
Prime the layer of bridging material or lining paper just as you would prime any other surface for wallpapering. Use an acrylic primer and allow to dry before hanging the wallpaper.
Hang the wallpaper as you would on any other wall surface. You've smoothed and prepared the ceramic tile surface in such a way you can now put wallpaper over it.