Congratulations on getting started with exercise!
You'll be surprised how fast your endurance will increase! Try to add a minute every day or so and you'll be up to 30 minutes or more before you know it.
One thing you could try while you're still building up endurance is to do several 10 minute sessions a day. It all adds up and is just as effective as doing it in one long session.
Also, mix it up. If 10 minutes on the bike is all you can do, add in a 10 minute walk and maybe 10 weights of some weights or some stretching. Every little bit you do adds up.
Most of us started out just like you and just keep working at it, day by day, until we got to the level we wanted to be at. You can do it!!