For the 4th line D, you can only play Defensemen here who are on your top 3 lines. You cannot add 8 defensemen to your lines! 

-----EVEN STRENGTH-----
     Forwards
     L          C          R
1 
2 
3 
4 
5 (LEAVE BLANK)
6 (STARTING LINE - choose line 1, 2, 3, or 4)

     Defensemen
     LD         RD
1 
2 
3 
Optional (4th line will play with line 4 forwards, if blank D-line 1 plays here.)
4
5 (LEAVE BLANK)
6 (STARTING LINE - choose line 1, 2, 3, or 4)

     Goalies
1 
2 

-----POWERPLAY-----
     5 Skaters
     L          C          R          D          D
1 
2 

-----SHORTHANDED-----
     4 Skaters(please specify which forward position)
     F          F          D          D
1 
2