Bike riding suggestions for new rider

Hello.  I am new this year to the sport of triathlon.  I have completed 2 sprints this summer and both of them I was no worse than top 5 in my age group swimming and running.  Biking on the other hand is another story.  First tri in June, biking was 3rd from last in AG, 2nd tri this past weekend improved my time to mid pack - 12 out of 24.  First tri was on cross bike and 2nd tri I purchased an entry level Jamis steel frame, carbon forks. 

My question - I am looking to increase my biking abilities over the winter (indoors).  How should I proceed with training and if videos are recommended, which ones specifically?  I will put the time in to training I simply know NOTHING about biking.  How much to ride, intensity, what is needed to train, etc.  The tri this past weekend 6 minutes seperated me from 1st place in AG and I gave up 5 minutes on my bike so I know where the work needs to be done.

I need some suggestions on how to train to build my speed/endurace/engine - all of the above.  Eventually new bike(s)/equipment might be in the future, however, I do understand I need the legs to pedal those fancy things.  I am strong and fit, just have never, ever formally riden bikes.  I appreciate the suggestions you may have.  Thank you!