To specify the default primary page add a hidden input with the name of capturepage. For example: <input type="hidden" name="capturepage" value="FILENAME.php">
Default Content Group
There is no way to do this through html. However, you can control what the default content group is when editing membership from /admin/memberships
Alternative: Use PHP
If this does not work for what you are trying to do (exa: You need it specific for a promotion, not a membership), the other way to do it would be to use php code and putting a hook for do-join.php page.
The best hook to use is a special one in the middle of the file.
To do it create a file called do-join-midhook.php and put the php code for editing the default content group in that file. There is an object for the member called $member that can be used with the method setPrimaryCGroup(#) for the primary content group.
A. When logged in as the admin go to Advanced Features then in the Misc tab there is a setting called "Default Capture Page" where you can change the default capture page that is loaded.
To edit the contents of the email that is sent go to Autoresponder Emails. Then at the bottom in the Misc Messages section click the link "Create New Account Email".
A. ~membership~ = Title of the Member's Membership ~password~ = Member's Password ~username~ = Member's Username ~fname~ = Member's First Name ~lname~ = Member's Last Name ~email~ = Member's Email ~phone~ = Member's Phone ~siteurl~ = The domain name of the site ~burl~ = The domain name of the site with /admin added to it (DEPRECATED) ~address~ = Member's Address ~city~ = Member's City ~state~ = Member's State ~zipcode~ = Member's Zipcode ~ip~ = Member's IP
A. ~membership~ = Title of the Member's Membership ~siteurl~ = The domain name of the site ~fname~ = Member's First Name ~lname~ = Member's Last Name ~email~ = Member's Email ~phone~ = Member's Phone ~username~ = Member's Username ~parentfirstname~ = Parent's First Name (5.0+) ~parentlastname~ = Parent's Last Name (5.0+) ~afname~ = Parent's First Name (DEPRECATED) ~alname~ = Parent's Last Name (DEPRECATED) ~sitetitle~ = The title of the site (system)
A. ~membership~ = Title of the Member's Membership ~password~ = Member's Password ~username~ = Member's Username ~fname~ = Member's First Name ~email~ = Member's Email ~url~ = Member's Redirect URL ~ip~ = Member's IP (5.0+) ~parentusername~ = Parent's Username ~parentphone~ = Parent's Phone ~parentemail~ = Parent's Email ~parentlastname~ = Parent's Last Name ~parentfirstname~ = Parent's First Name ~surl~ = The domain name of the site (DEPRECATED) ~siteurl~ = The domain name of the site (5.0+) ~burl~ = The domain name of the site with /admin added to it (DEPRECATED)