Typing the words "first home savers account" into google brings back this link:

http://homesaver.treasury.gov.au/content/default.asp

Doesn't look like it has an "if interested register here" button – so I guess there probably isn't one. The FAQ on this subject says:
"You will need to complete an application form which will be available from your FHSA provider. Applicants will need to satisfy the eligibility criteria to open an account, and must meet the withdrawal criteria to access their funds."

So you'll probably have to go talk to some banks and ask them what they're likely to offer and see if you can pre-register interest with them.

Cheers,
Taryn