Once you have selected a domain name to host your landing pages on (under 'Create Campaign') you then have the option to rename the extension that your landing pages will use. This can improve click-through-rates and relevancy. So, for example, you could rename:

www.domainnamehere.com/5gHHty4455Thxz

to:

www.domainnamehere.com/free-dating

If you would like to change the URL path later, you can do this by clicking on the Edit Campaign button from within your campaign overview.