A picture would help.
Normally there is a big reefing eye in the tack of the mainsail, and you hook it onto a hook at the goosneck. A reefing outhaul tensions the foot of the sail, and don't pull the halyard tight until the outhaul is tensioned.
When you tie the reefing ties, remember not to tie them round the boom.
Practice all of this in port, with the wind ahead of your boat.
It is far easier to do in port than on a bouncy sea.