Who Can Appeal
Only a defendant in a small claims action can appeal. If you are the plaintiff, you gave up this right (it was on form SC-100 that you filed with the court.) However, if you were sued back on a defendant's claim (e.g. Form SC-120) then you have the right to file an appeal.
Once it is determined that you CAN file an appeal, fill out Form SC-140. This form is available at: http://www.courtinfo.ca.gov/forms/filable/sc140.pdf This form can be filled in online and then printed. You can then turn this form in to the court where your case was heard. There is an additional $75 filing fee. Note: some counties permit the filing of an appeal electronically. If the appeal is filed this way, there is USUALLY a surcharge as well as the $75 fee. Check with the local court to determine if this option is available.
Obtain a Court Date
Once the appeal is filed, a court date will be given. It is usually best to file in person - if possible - as many courts may give the filer an option for a court date. Once the court date is known, prepare for your case.
Trial De Novo
California law requires that a Small Claims Appeal, or Trial De Novo, be heard by a new judge (e.g. one other than who heard the case the first time.) At this new hearing, attorney's are permitted to argue on behalf of both parties (plaintiff and defendant). However, the rules of evidence are not supposed to apply. But it is up to the individual discretion of every judge to determine how his or her courtroom is to be run.