New Restfull API Other Objects feature

[Get-Gaming]

So we're able to retrieve and post custom fields now but i don't quite understand how i can do that. I only got as far as using the parameters.

$curl = curl_init( $communityUrl . 'cms/records/2' );
                curl_setopt_array( $curl, array(
                CURLOPT_RETURNTRANSFER	=> TRUE,
                CURLOPT_HTTPAUTH	=> CURLAUTH_BASIC,
                CURLOPT_USERPWD		=> "{$apiKey}:",
                CURLOPT_POST        => 1,
                CURLOPT_POSTFIELDS  => "category=$insertcategory&hidden=0&title=$title&author=$this->memberid&fields[7]=$this->departure&fields[8]=$this->arrival&fields[18]=$this->income&fields[11]=$this->cargo&fields[9]=$distance&fields[10]=$consumed&fields[12]=$this->mass&fields[13]=$trailerDamage&fields[14]=$this->brand&fields[16]=$this->fromcompany&fields[17]=$this->tocompany&fields[15]=$this->model"
                ) );
                curl_exec($curl);

Left api and url out of it here. This works. But how could I also edit a member with this post?

If not possible can I edit custom fields through a seperate curl then? If so how?