Chapter 6 of The California Landlord's Law Book: Evictions explains how to file and serve the unlawful detainer complaint. Landlords who have been unsuccessful at personal service may serve the complaint and summons by "posting and mailing," which involves leaving a copy of the court documents at the tenant's front door and mailing a second set.
Landlords need to obtain court permission first. They may use a form developed by the Los Angeles Superior Court for this purpose, "Application and Order to Serve Summons By Posting For Unlawful Detainer" (it will work in any county). Towards the top of the form, beneath the text box with the plaintiff's name, there's a box for the name of the superior court (such as, "Superior Court of California, County of Marin").
The tear-out version of this form, in Appendix B, includes the words "Superior Court of California, County of" that are followed by a blank space, into which the user can write or type his county name. But the electronic file currently in the book has the words "Los Angeles" embedded in the form, doubtless because the form was developed for use in LA and the designers didn't anticipate that it would be used elsewhere.
The corrected version of the file omits the words "Los Angeles," and in their place gives users a fillable field, just like the other fillable fields on the form. Type the name of your county in this field.