Select from the Entity Framework of a table resulting from an N to N relationship

Question

I do not know if it is very clear the question, so I will try to illustrate the scenario better.

I created a table of Activities and a table of Users, in the table of Activities I have a responsible for it and I can also have some users associated with this.

In the mapping I put this relationship and left explicit that should be created a new table with the name X and properties Activity and User, for example, as expected the table in the bank was created normally and all relationships are working, but a question appeared when the need arose to select the activities to which user X is associated, I can not make this select.

I need to create the Dbset from this table to be able to do this or is there another way? I haven’t created yet, because I haven’t seen the need since I can include, change and delete normally associated users.