Is it okay to do two workouts? First one upper body, and the second one legs?

In general:

Assuming you are healthy (although I don’t like to assume, but in this case I will make an exemption for the sake of the question), the answer is yes. I would take at least a day off between workout days to give the body time to recover. The duration, intensity and frequency they all depend on your goals. Also I would do different types of exercises each day for variety and muscle stimulation. There are many ways to approach this. I would suggest to alternate heavy lifting days with functional training days (TRX, body weight, kettlebells, ropes, sandbags, etc.) to optimize not only muscle growth but also the functionality of your muscles/body.