You can connect with a creative in several ways on a Creative Commission, the main way is to post a brief which will outline your project, (deliverables, timeframes, budget) from there creatives on the site will decide whether its a project for them and pitch to you, (via the site). 

You can connect with a creative via an open brief which is a call out to creatives to share their work with you, you're then able to build out a network of creatives in that particular discipline and who meet your requirements.  

You can also follow a creative and once following you are able to direct message them via the site.