Want to loop through Drop Down Lists and Insert Value into Junction table ??

hi,
I have 3 drop down lists on a form that collects data from a visitor.
 
Each DDL shows a list of Music Genre and the User can make up to 3 choices ( 1 selection from each DDL)
I want to loop through the DDL´s and Insert the GenreId (int) and UserId (Guid) into a Junction Table  called
UserGenre which has UserId and GenreId as Primary Keys.
In C sharp - How can I loop through and get each DDL selected value (If chosen) from the form and insert to table??
 
Many Thanks
Prontonet
 
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