I have a Data Extension that stores user details like FirstName,LastName and Email. Is there any way that allows us to pass these values to our Salesforce CRM. Maybe as a record in Contact?
Depends on your use case, but generally you have two options:
Use Journey Builder Sales & Service Cloud activities to create/update data on Salesforce CRM. You need to have the Marketing Cloud Connector.
PS: don't forget to link your DE in Data Designer to be able to use it in your Journey.
Use a CloudPage to update data on CRM by using
UpdateSingleSalesforceObject functions. Check the doc for more information: