Make sure you have adequat sports equipment, shoes and outfit for indoor sports. For this, ask a professional for assistance on what to get.
Make sure you adjust your bike to your size (height of the seat and of the handle bar, and if possible the length between the two). The height of the seat must allow you to almost touch your elbow (when your hands are on the handle bar) with your knee when your leg is bent.
After each session don't forget to stretch, to relax and to drink on a regular basis during the day.
Please respect instructions during the sessions especially those pertaining to pace.
From the start, control your breathing while inhaling and exhaling deeply from your abdomen and thorax.
Keep breathing comfortably, but also feel altogether comfortable.
Comfort and enjoyment should be your priority.
Ideally, try to workout on Monday, Wednesday and Saturday or Sunday. If you choose to workout on different days make sure you leave 2 to 3 days between the sessions.
Now go!
GOOD LUCK.