Try to find a voice coach or singing instructor that fits your needs. If not, there are numerous videos on youtube that can assist you, but keep in mind that almost anyone can upload a video on youtube, so take extra care when trying these at home.
I'd personally suggest "singing for dummies", I think it's a very well rounded book, with great exercises that will answer most every one of your questions! And try to sing over your favorite songs! The more you sing, the more you'll be a better singer!
Find a singer you love and try to fit in their repertoire. Watch how they do it, carefully, and try to immitate at first. Then, try it over some karaokes! And most important: have fun!