i agree with andy

while changing chain rings is not rocket surgery
it takes some knowledge to properly select a chainring
that will match the crank and chain

and then the crank and bottom bracket assembly usually has to be disassembled
and the chainring(s) replaced
and the whole thing put back together
including likely derailleur adjustement

now i am all for do it yourselfing everything possible
but given the misidentified bike
and the fact that the op referred to the visibly damaged big chainring as
the second gear
both led most posters on a wild tooth chase
and
betrayed the op as someone who should be consulting an experienced person
who can lay hands on the bike