Muscles do not develop that easily. Usually, "big and muscular"
arms for females are because the muscles and fats are together.
You can't spot reduce fat from anywhere you like other than by
things like liposuction; you have to lose fat from the body as a
whole.
Start by planning a full body workout. It does not have to
necessary include weights; body weight can suffice at most times.
That means, you can try out some of the workouts in the stickies
without any weight or barbell.
The key to any exercise is intensity, and full body.