Joni, Wbtravis' advice is good.
If you can get up to White Mountain, (the drive is a bit more arduous than getting to Whitney Portal), the hike is easier -- a jeep trail to the summit, and you start at 12,000'. Doing that would give you and idea how your body will react to the altitude.
Just before your hike, my favorite place to acclimate is Horseshoe Meadows, 20 miles off the Whitney Portal road. I like to spend two nights there (at 10,000') before I try hiking to a 14k summit.
If you go to any of these places, you won't be alone. There are always people to connect with during the summer.
