I know. I truly understand. I wish I could lose 100lbs by August. But we have to go into these changes with a level head and realistic expectations.
There are some great starter tips for weight lifting on the site, and people are very happy to answer questions. Cardio is great for the body, but it won't build muscle as well as strength training/weight lifting can.
Believe me, if you start now and stick with it, you'll see changes by the time August comes around. You may not be at goal, but you'll see changes. And if you DON'T start... then August will still be coming around either way.
You'll find a way to start and keep with it.