You are flying on Southwest. Number 1 there are no reserved seats. You should check in online at T-24. This assigns you a boarding "group" either A(16-60,) B 61-120 or C121 +
Unless you are flying on business class fares which get assigned group A 1-15, you then present yourself to the boarding area queue in the correct corral and wait for boarding that begins about 10 min after your plane arrives or 20 min or so before departure. If you were travelling with a child then you should have presented yourself to gate agent as soon as you arrive at gate to receive a special preboard sleeve that enables you all to board as a family usually before the madness begins.
As said earlier there are no assigned seats, the A Business class boards then the rest of the A group followed by B and C and so on.