Adapting a pattern to mittens

If I’d like to modify this arm warmer pattern into a mitten pattern, how might I go about this? This would be my first mitten project.

I don’t think that would be hard at all.

I’d look at some mitten directions, the hand shaping part. If you find one the same guage as your mit pattern, just switch over the the hand shaping part once you get past the thumb.