You must be enrolled in Defense Enrollment Eligibility Reporting System (DEERS) to get a DSLogon account which you will need to signup (sponsors are automatically registered in DEERS, however, sponsors must register eligible family members)

Update DEERS (if needed):  https://tricare.mil/deers)

Facts and Directions  https://www.ebenefits.va.gov/ebenefits-portal/downloads/eBenefits_factsheet.pdf

Sign in/Register: https://www.ebenefits.va.gov/ebenefits/homepage  (you must have or create a DSLogin to sign in)