In your case you will need to compare the angle from the character to mouse cursor. So you might use conditions "System is between angles" , with expression angle(Character.x, Character.y, Mouse.x, Mouse.y)
> angle(Character.x, Character.y, Mouse.x, Mouse.y) is between -45 and 45 gegrees
Character set animation "Right"
Could you provide a little more information? Sorry I'm not very smart. Heres what i did imgur.com/a/HccbES0
It just randomly sets my player animation to the right, regardless of where my mouse is.