Your LLC paperwork should provide the structure of your business. The C in LLC stands for corporation, which would suggest a C-corp or an S-corp, but there are LLPs as well. If you filed for an EIN the EIN paperwork you got from the IRS will tell you the business structure you filed as, the tax return you are supposed to prepare, and the due date.
Generally how it works with S-corps and partnerships is that the organization files a tax return (1065 for Partnerships, 1120-S for S-corps), which is due 2 1/2 months after the organization's year-end, March 15 in most cases. Each shareholder or partner gets a K-1 for their share of the profits. The organization pays no tax, it is just reporting the income and each partner/shareholder is responsible for reporting and paying tax on their share of the income. In the case of income from a rental property, the information reported by the organization flows through to your individual tax return and gets reported on your and your friend's individual Schedule E.
A C-corporation is different and pays its own taxes. There is more that needs to be done in setting up a C-corporation, so I doubt this is the business structure you and your friend elected.
