What is a good fitness program to do?

I have a treadmill at home a exercise bike,and a trampoline. I might be getting the steps type thing. How would i conduct my workout and how long should it be?? how long should my warm up be before actually exrtcising and my cool down after??? I’m new to this so any tips i’m open!

stretching (legs)…3-5 min.- treadmill 20- 30, bike: 20 min., trampoline 10 min., stretching +cooling down 5 min.

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