i have no idea what coin.bn is! are you by any chance talking about this: https://coinb.in/#newTransaction

in any case, CPFP is Child Pays for Parent and it means a receiver pays the fee of what he received, to put simply.

as a sender it is best if you pay higher fees in the start, and also use opt_in RBF so that you can increase the fee. you can use Electrum for this easily.

but to use CPFP as a sender you can do this:
if your transaction is creating two new outputs (meaning you have a change address that are receiving the remainder of bitcoin in it) you can use CPFP on that.

i am not sure which wallet lets you do that, i have never had to look it up!
but technically you spend that transaction and pay higher fees, this fee needs to cover the fees for the previous transaction and the new one. for example if the previous tx needed 0.0006BTC fee and the new one needs 0.0004BTC, in your new tx (the CPFP tx) you pay 0.001BTC.