So this may sound crazy but talk to yourself. Seriously, I mean act like you are going to teach someone what you know or find someone to teach. Start by verbalizing what you know then think of some questions that someone may ask you and if you don't know look it up then teach some more. I have always felt the best way to learn is by teaching because it uses verbal, visual, and interactive/cognitive thinking.
For example: CHF is the loss of the ability of the heart to pump blood. Why? Various reasons including MI, HTN, bottom line the heart has had to work too hard, S/S well class that depends on the side of the heart that is affected. Right - generalized edema Why? because there is a back up of blood due to the decreased ability of the heart to pump so it accumulates in the body. Left - SHOB, orthopnea, pulmonary edema, and right sided failure too. Why - because the blood is now backing up into the lungs and they are literally drowning. There is just not enough pressure (due to decreased muscle strength) to adequately empty the heart (low BP).
Also relate the body to things that you know. Again, with CHF, a failing water system - someone threw a cheeseburger in a well (clogged arteries leading to MI). The cheeseburger went into the pipes and got stuck blocking some water but the pumps know that more water must go through them so they continue to pump harder (HTN) to get more water then the cheeseburger is dislodged or someone removes it (cardiac cath). Well the first pump (right side) is tired after all that and burnt out so it quits. Well eventually the pipes get full and the well is overflowing even though the other pump (left side) is working hard to get all this water circulating because now its doing the work of two pumps! It can't possibly keep up because it wasn't designed to pump that much water. So the water backs up into the well, into the pipe, into the first pump, and into the pipe between the two pumps and now you have a problem. The pump will work but will eventually get tired to from working two jobs and it too will quit. There are quite a few other components involved with CHF but you understand the concept and how it is a chain reaction. Many systems and functions of the human body can be likened to other things that we know and use daily and it makes it much easier for me to learn that way.
Just an FYI I taught myself this way through school and I was one of the top students in the class and passed NCLEX on 75 questions in 45 minutes or so. Good Luck!