SQL tables relations
@Wozniak form what i can see you need the sql syntax t build this structure ! to do so use the syntax belew :

create table Activity_Types(
activity_type_id in,
activity_name varchar(20),
PRIMARY KEY (activity_type_id)
);


create table Activity_Log(
activity_id int,
user_id id,
activity_type_fk id,
activity_date date,
PRIMARY KEY (activity_id),
FOREIGN KEY (activity_type_fk) REFERENCES Activity_Types(activity_type_id)
);


Where foreign key that makes the relation is hold on the Activiy_log table under the activity_type_fk column. 
 to join this tables just use this columns !