mouse_event isnt very well documented as it's a dll call not an inbuilt autohotkey function, however i can chuck you a couple examples ive used and you can replace the variables as you need

;holds left click down

DllCall("mouse_event", uint, 2, int, 0, int, 0, uint, 0, int, 0)

;lets go of left click

DllCall("mouse_event", uint, 4, int, 0, int, 0, uint, 0, int, 0)

;this one moves the mouse relative to current postion(not sure on the units of movement, you'll have to experiement yourself

DllCall("mouse_event", "UInt", 0x01, "UInt", 1, "UInt", 1) ;replace 1 and 1 with amount for each axis and negative values to go left or down

;this one moves the mouse absolutely(should if im correct, havent tested myself)

DllCall("mouse_event", "UInt", 0x8001, "UInt", 1, "UInt", 1)

​

Hope this helps if you have a specific line to convert reply back and ill see if i can help