HI Punit, Start with Trailmixhttps://trailhead.salesforce.com/en/users/strailhead/trailmixes/prepare-for-your-salesforce-platform-developer-i-credential
You can register for certification on the Webassesor site https://www.webassessor.com/wa.do?page=login&branding=SALESFORCE
If this information helps, please mark the answer as best. Thank you
Start with Trailmixhttps://trailhead.salesforce.com/en/users/strailhead/trailmixes/prepare-for-your-salesforce-platform-developer-i-credential
You can register for certification on the Webassesor site https://www.webassessor.com/wa.do?page=login&branding=SALESFORCE
If this information helps, please mark the answer as best. Thank you