Hi!
What wall do you want to put the tapestry on?
I think the simplist tool to use is the Polygonal Lasso Tool. Make your selection, then if you want to, you can save it by choosing Select>Save Selection, and have it available if you need to redo the changes. With the selection active, Make sure you have a new layer active, and then you can either fill with a new color, or use the Hue/Saturaton Adjustment layer and use your saved selection to create a mask to only have the color where you want it.
If you want to put a tapestry, then I agree with the suggestion above to import it into a new layer, and then use Transform>Distort to change it to the correct perspective.
Here is an example of the bottom part of the counter, using the Polygonal Lasso tool, and then once I had a selection, I clicked on the Hue/Saturation Adustment layer and it automatically created the layer mask in the shape I created.
I hope this answers you question, if not let us know!
Michelle
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