Ronocerous

My quick question is: will riding on my trainer for 1/2 hour at HR 130 or so three times a week help build my aerobic base?

I'm not is great shape - ride about 2500 kims per year commuting but I couldn't keep up with you folks. I'd like to do a century this summer. I spent a lot of time here reading posts on aerobic training and read about the 3 hour rides. There's snow on the ground here and besides I don't think I could do a three-hour ride anyway.

Thanks for your help.