Once you have the phone on your network you just need to get the IP from the Phone and then enter your SIP credentials:
SIP Username: Usually generated by the hosted platform like a 6 digit number.
SIP Password: Sometimes generated by the platform sometimes chosen.
SIP Domain: something like sip.pbxww.com for instance.
Once you have your Login credentials just navigate to the Phone IP address using a browser and then ender those details as follows:
Under Option Ext 1, Account 1 or User 1
SIP Username = User ID
SIP Password = Password
SIP Domain = Proxy
The Phone might need a reboot after but this is the most simple setup. This can vary from one provider to the next.