Typically, and I'd check your pattern instructions to be sure, M1L means that you'll lift the strand one row below, from front to back with the left needle, and it will slant left. M1R is similar, except that you'll lift it from back to front with the left needle.
Wisdom is knowing what to do. Skill is how to do it. Virtue is getting it done.
That which does not kill you, isn't trying hard enough.