The best opening move for 5-1 in backgammon is 13/8 24/23. One safe builder, a small split. Watch it on the board, then read the idea behind it.
The idea behind the move
With 5-1 play 13/8 24/23: one checker steps safely to the 8-point and one back checker takes a small step to the 23-point.
What comes next
The small step gives the back checker more rolls to get free later. There is little risk, and you keep all your key points.
How to read the move
A move like 24/18 means one checker goes from your 24-point to your 18-point. Points are counted from your side: 24 is the farthest, 1 is the deepest in your home board. “(2)” after a move means you play it with two checkers.