surely exercises with dumbbells is the best way to tone your arms! the easiest exercises are to lift up your arms with dumbbells. but it's better for you to seacrh in the internet for exercises (with video). If you will work every day for around 15-20 min i am sure you will see great results within one month! wish you good luck!
Weight-Lifting to Tone Your Arms
Do bicep curls. Stand up straight and hold a dumbbell in your hand so your palm is facing outward. ...
Try the shoulder press.
Do the standing "V" raise.
Complete sit-up pullovers.
Use small weights to do weighted punches.