I currently follow this step by step in order to scan a URL :
Prerequisite said :
"Check the Host Assets in your account (Assets > Host Assets) to be sure the IP addresses (full IP ranges) that the hostnames will resolve to are in your account. If the external scanners cannot resolve a hostname to an IP address, vulnerability assessment of the host will not occur. And if any resolved IP address is not in your account no scan results will be reported."
However I have no hosts assets !
How do I add a host asset ?!