What will happen if I had a private show via Skype with a 14-year-old?

15 to 25 years. Hire a good criminal defense lawyer.

This is serious. Sending any kind of electronic lewd images to people under age can have severe consequences, including being forced to register as a sex offender if convicted of certain crimes. Don't talk to the police if they ask you to and retain an experienced criminal lawyer in your area, preferably one with experience in sex crimes if the police ask to speak to you or you are charged. Also, stop sending such messages to people regardless of whether you know their age or not because you can never be certain.

You could be charged with a violation of California Penal Code Section 288.2 INTERNET SEX WITH MINOR 288.2. (a) (1) Every person who, with knowledge that a person is a minor, or who fails to exercise reasonable care in ascertaining the true age of a minor, knowingly distributes, sends, causes to be sent, exhibits, or offers to distribute or exhibit by any means, including, but not limited to, live or recorded telephone messages, any harmful matter, as defined in Section 313, to a minor with the intent of arousing, appealing to, or gratifying the lust or passions or sexual desires of that person or of a minor, and with the intent or for the purpose of seducing a minor, is guilty of a public offense and shall be punished by imprisonment in the state prison or in a county jail. Because it can be punished with state prison or county jail this is a charge that could be filed as a felony or a misdemeanor. If convicted of a misdemeanor you could get up to a year in county jail. if convicted of a felony you could do 16 months, two years, or three years in state prison.

Arrest and conviction. You better get a lawyer.

How did you find out that she was 14? How old are you? These things need to be known before advice can be given.