How can I reach higher tenor notes?

There are some vocal exercises you can find right on youtube that may help. I may be preaching to the choir, as it were, but a couple thoughts are imperative to accept: as you age and grow, your vocal cords do as well. Vocal cords are stretched by muscles. Muscles can be exercised. Don't overdo your voice or you'll lose it forever!!!! I recommend for quality's sake as well as exercise, that you avoid falsettos like the plague unless there's no avoiding them. Every time you sing, you exercise your voice, but you waste valuable exercise time by singing falsettos (IMO). Singing lots will not only exercise your voice, but will also increase your range. For a quick warm-up, try 1/2 ounce of lemon juice followed by 5 minutes of normal conversation. Then head for a bathroom or waste basket and half cough / half clear your throat. (kind of a growling "HURH") You'll bring up a hunk of crud the size of your head and your voice will almost amaze you! Best of luck!