A photo of your filter would be helpful.
What year engine?
What brand of filter unit?

Typically, oil flows into to filter from a line near the rear of the block into a fitting high on the rear side of the filter unit. The oil goes into the canister on the outside the filter cartridge.

The oil then moves through the filter cartridge to the center of the filter cartridge and into/out a hole near the top of the hollow center post.

The oil exits the bottom of the unit through the bottom of the hollow center post.