Just be patient and spend some time on the bike. Cadence, speed, and relative comfort will come in time.
If you want to monitor your cadence and speed, I recommend you pick up a computer like
this one. It is cheap and effective.
For now, just keep yourself in a zone of easy to moderate effort at a leg spin slightly above what your legs want to do. Many people seem to have a natural cadence of around 75-80. Gear up or down to stay in your effort zone.
Once you get comfortable on the bike, then consider at least a 3 day format. One day is short and hard efforts (maybe 20-30 min total out of an hours ride. Do short bursts, recover, and repeat then finish off with a steady pace), another day is steady moderate pace, and a third day of easy to moderate pace with distance. Log your efforts and your distances. On the distance day add a little more distance. On the hard days note the gear, cadence, and effort. Do a little more each time. If you ride more than those 3 days then make them fun rides.
Results? You'll see nice gains (strength and fitness) for sure.
Don't forget to cooldown and stretch. Make that a mandatory part of your ride. It is just as important as the rest.