I am trying to tone my arms. What are the appropriate weights for a female?

You should be able to do three sets of fifteen reps with the weight you're using. The last rep of the last set should be difficult to almost impossible. This will tell you you've got the weight right.

There is no "appropriate" weight. It varies from person to person and depends on how fit and experienced you are.

Three sets of fifteen reps will tone and harden your arms. Three sets of ten reps with more weight (remember the last one should be on the verge of failure) will increase strength and bulk. DON'T WORRY about bulking up. It's very, very difficult for a female to bulk up very much without steroids and a LOT more work than a man has to put into it. Any bulk you do add will look REAL good.