Ef code first with existing database

Suppose I have two database tables, say tb1 and tb2, with

[tb1]
 id      primary key
 name
 lastname
 
 [tb2]
 id      primary key
 tb1_ID  foreign key
 phone_no
 degree
 grade
 

Relationship tb1 may hold multiple record of table two. i.e: one to many relationship.

For this relationship I need an entity that hold all column of tb1 one and only one column on tb2 (say only ph no.).

Suggest me the easiest possible way.

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