:salam:
We can't manually forward threads to any user. If you post a reply in her original thread, then she will automatically get notified if she has chosen to receive email notifications.
As an alternate, you can tag any user on your thread by using the @ symbol. For example, if you write
@
AabiruSabeel
then I'll get notified for it. Make sure the spelling is correct.
To become a full member, you just have to keep participating in the discussions on the forum and have at least 25 posts. Then the system will automatically upgrade your account.