A4988 with mks gen L v. 1.0

Hi all.

This time i have big problems to start my nema17 motors from mks gen L board.
I have install Marlin 2.x and it work good. I have also look 2 days many many Youtube clips. But im not understand how to start motors from my computer or my lcd. I have put vref to 1.3v for testing. Can Anyone help me please to check what im doing wrong. I have also enable a4988 in Marlin fw.

Thanks

/Willy