If you are "not so good in math", then in order to understand the notation, you have no choice but to get better. You need the equivalent of a course in college-level differential calculus and some familiarity with the literature on function minimization. With some mastery of those subjects, you will realize that this is actually not very complicated material, and fairly straightforward to program.
While the notation is compact and convenient, there are lots of other ways to explain the approach and with some searching, you may find explanations that are easier to understand, as well as code examples.
Getting the concepts to work well in practice is another matter entirely, because of the presence of arbitrary parameters that have to be chosen with care. That effort is the subject of much of the published literature. For experimentation it is useful to start with a mobile robot simulator like MobotSim. http://www.mobotsoft.com/