In Salesforce we can easily create new records into objects by using the Create New drop-down list on the sidebar of any page in Salesforce.

also we can create record by selecting any object and click new button to create records.

Once you enter all the required details in the record fields click save. When you share records with other users, you can assign them different levels of access to the records.The available access levels are:

ACCESS LEVEL	DESCRIPTION
Full Access	User can view, edit, delete, and transfer the record. User can also extend sharing access to other users; however, the user cannot grant Full Access to other users.
Read/Write	User can view and edit the record, and add associated records, notes, and attachments to it.
Read Only	User can view the record, and add associated records to it. They cannot edit the record or add notes or attachments.
Private	User cannot access the record in any way.

• Beyond setting the organization-wide sharing defaults for each object, you can specify whether users have access to the data owned by or shared with their subordinates in the hierarchy. For example, the role hierarchy automatically grants record access to users above the record owner in the hierarchy.
• By default, the Grant Access Using Hierarchies option is enabled for all objects, and it can only be changed for custom objects.
• To control sharing access using hierarchies for any custom object, from Setup, enter Sharing Settings in the Quick Find box, then select Sharing Settings. Next, click Edit in the Organization Wide Defaults section.
• Deselect Grant Access Using Hierarchies if you want to prevent users from gaining automatic access to data owned by or shared with their subordinates in the hierarchies.

You can also grant wider access to data using sharing rule. To do this go to sharing setting from setup and click new from object sharing rule example click new from “Account Sharing Rules” then setup and save.

Also you can do manual sharing of records by clicking the sharing button from records.

NOTE: If you encounter an error when selecting the Full Access option, you no longer have the permission to set full access on records. Contact your administrator to determine if this access is necessary.

This training information is very useful to learn about record creation and its security levels in salesforce.