where do i post if i want my ban to be lifted?

it wont b

You don't post because it won't be lifted.

if you want to contest and argue your ban you submit a support ticket for review... and explain why , etc etc they will look at it... look at your case and then 99.9999% of the time not unban you ... but you can try

If it is a suspension from the boards, you are welcome to come talk to us on the Boards Moderation Discord.

I apologize, I had previously told you that you could make a post in Player Behavior for help with this issue. However that is not correct. You would need to contact Riot Support by sending in a Support Ticket.