Answer:
Say the letter "O" but try say it without the 'w' or 'h' at the end (not oh)
you pronounce the t at the end when the thing your talking about (haute is an adjective) is feminin or if the next word in the sentences begins with a voul
In your case haute is in its feminin form so ye you have to pronounce the t (a very basic view is that if the word has an e at the end it is feminin - although as it is common with french there are LOADS of exceptions)
hope it helps