Hi,
you should be able to add your trial account HCP HANA system to the HANA Studio by selecting "Add cloud system", then filling in your trial account data: account name, user name, password. The popup is different to the one you show above (which is for adding on-premise systems).
Another thing you could do is just use the browser-based IDE within HCP; it contains more or less the same functionality as the HANA Studio. You will not really need the Studio for most activities.
Then, check SCN (or Google) for HCP end-to-end examples on HANA development. There are lots of examples and blogs out there, most of them can easily be done on a trial account for HCP.
Regards,
Trond