How can I create a small dressing room contained by a corner? Like with a mirror, a curtain around all sides, and satisfactory room...

Like with a mirror, a curtain around all sides, and satisfactory room to actually be able to return with dressed.
If you are likely to spend a little money, you should consider buying a room divider. Those are classy and perfect to set up a wall for a dressing room. Pier1 have some stylish ones you might want to check out. most diy stores sell a shower curtain frame for clawfoot tubs. A mirror and one of these frames would work great for what you're trying to do.
Hang curtians (or a pretty sheet) from the ceiling with tack, or a towel bar.

Or, you could build a little stand out of sprinkler PVC from the home amendment store. You'll need a pair of cutters, but it will fit together resembling tinker toys. I don't think you need to use epoxy resin since it's for indoors. Then cover the stand with pretty fabric or a shower curtian. It's lightweight so you should know how to move it around too.
Answers:    You can hang up long and cute curtains and have a rack beside some clothes and some accessories and maybe for a moment table with makeup and a mirror of courseVOTE AS BEST ANSWER PLEASE
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you could hang a mirror on the wall and after put like shower curtains or windsor curtains on the sides,
that would be pretty awsome! :) this is pretty awsome, not what ur looing for but some ideas:
http://images.google.ca/imgres?imgurl=ht...
Aah Confuses say buy Shoji screen.
http://www.orientalfurniture.com/orienta...
Just an opinion I don't know what your decore is or if it matters. This you can have privacy and if it take to much room you can push it back till you need to go and get behind and dress.
hang up curtains around a corner from the seal U can grab a towel and grab some nail and pin it to there