To trust in the Force is probably one of the hardest but also easiest parts of being a Jedi. You need to think back to the time when you were a child. Children have such an open mind to things no matter what they are. As you grow older and become more set in your ways, most people lose that open mindness in life. You need to take down that barrier you have set for yourself and open your mind to accepting the Force even though you can't understand every facet of it. Always strive to learn, apply, and understand the force as much as you can but it is always evolving so you will never know everything about the Force. Don't worry about that, accept what it is and allow it to become a part of who you are. If there is any question in your mind about the Force it will not become a part of you but once you open up to it, it just becomes a part of you.