Are you trying to file a tax return for the LLC which is owned by another LLC, or are you trying to file a tax return for the LLC that OWNS the other LLC?
If you are filing for the LLC that is not a S-corporation, and for which you are the sole member, then you fill out Schedule C on your Form 1040. That LLC is treated like a sole proprietorship and is reported on your personal income tax.
If you are filing for the S-corp LLC, then you fill out Form 1120S, for which there is not a Schedule C, only a "Deductions" Section on the first page of the form.
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