When addressing a mailing or package to an individual "in care of" another party, you must follow a specific format. That format includes the name of the individual, the name of the owner of the place that is receiving the mail and the address.
Use the top line to identify the desired recipient
Enter the name of the person to whom you are sending the package on the top line.
Enter "c/o" and the name of the receptacle or residence owner on the second line
If you are mailing a package to John Doe at the address of Jane Doe, you would write: John Doe C/O Jane Doe
Complete the address as usual
The remainder of the address should be written in the usual format, including house number, apartment number, street name, city, state, postal or zip code, and country, if needed.