First time: your therapist's invite email contains a sign-up link. Click it, set a password, and you're in. The link is valid for 7 days; if it has expired, ask your therapist to send a new one.
After that: sign in with your email and password at your practice's login page.
Forgot your password? There is no self-service reset. Contact your therapist and ask them to help, they can send you a fresh invite link.
Change your password any time from Profile → Change password.
Language: the mobile app has an English/Hebrew switch on the Profile tab that changes the whole app, including layout direction for Hebrew. The web portal has the same switch on the Profile page.