Try a small barre first
Lay your index finger just behind a fret across two high strings. Avoid placing it on the metal fret itself. Press only hard enough for both strings to ring clearly, then try three strings.
Build a full shape
An E-shape barre at fret 1 makes F major. Your index finger replaces the nut while your other fingers form the E major shape one fret higher. Check strings separately and relax between attempts rather than forcing your grip.
Why is my barre still buzzing?
Your hand may need time to adapt or your finger may be too far from the fret. Keep attempts short, adjust your posture and stop if it hurts.