I need some advice on how to train.
I ride fixed gear right now and I want to get faster and be able to ride longer distances. I only have a little bit of time however as my school schedule is very strict. I can bike maybe an hour a day, and more on the weekends. I was also thinking of joining the Cycling class at the local LA Fitness.

Right now I can only do about 6 miles at a 16mph pace. I want to be able to do 20-30 mile rides at a 20mph pace and more. I also want to be able to do a century within a year.


So basically, what training method would be best for me to quickly build speed and endurance?
I'm an incredibly perfectionist person about this kind of stuff so detailed advice would be great. I'm not too concerned with diet right now but I'll change it if I have too. I'm 5'8" and 135 pounds and I eat around 2500 calories a day.

This is my bike right now:

I am getting drop bars for it soon, and I am also getting a Sugino Messenger crankset soon also.