There may be a section at the top of the enlarger that also has a bellows that you set for 35 mm.

Then, First you need to adjust the height of the enlarger for general focus. - next use the bellows for fine focus.

Make sure that the negative is in a neg carrier....
The lens should be at f5.6 or f8 or f11 (usually a middle aperature)
These are real basic steps...but maybe as a beginner you are missing something.

Is there anything here that you are not doing?

If you are still stumped....

Can u upload a pic of the enlarger?

Marko