I have almost the same bike. Mine is the Secteur Triple and what I like best is that it is versatile. The bike will take 28mm tires and has mount points for a rear rack. In cool weather, Spring or Fall, The rear trunk will hold extra layers, a really warm fleece hat, gloves or whatever might be necessary for a change in weather.

Anyway, your question was about training. There is a large amount of free info on the web from experienced trainers that can be easily googled. I prefer to curl up with a book. Denver Fox recommended "Cycling Past 50" by Joe Friel who is a well regarded trainer.

Generally, training begins with a process called building a base in which your body undergoes changes to accept the physical load being imposed. Even long time cyclists, after a layoff, begin with building a base. At some point you begin to be somewhat stronger and a bit faster with not too much discomfort. This point, no doubt, will vary from person to person. In my case, I get a bit faster every year but as a 73 y.o. man I don't sweat it if I'm not the fastest wheel in the peloton. In fact, I'm close to the slowest rider on club rides but this is not a problem for me.

This is early season so I'm in a base building phase. My rides so far this year have been from 20 to 50 miles. Last year the longest ride was 71 miles with 30 to 60 miles more typical. It is fun to go fast but as an asthmatic I don't have the lung power to sustain hard efforts. Still, every year so far I'm a bit faster and can ride longer. My mantra is to do as much as I can as long as I can. Enjoy the ride.