I am going to build a wall with 2 door openings using metal studs. How do you frame for the door openings? Is it necessary to use wood in the opening?

Thank you in advance for your assistance.

It is not necessary, although wood works well. I framed by basement with metal studs and used wood 2x4s for the door openings.

Here is a Link to some instructions for metal studding.

You can use two metal studs facing each other.