An adjustable-height pull-up bar, suspension trainers or gymnastics rings. Alternatively, if you can find a bar that is roughly waist-high and another that is chest-high you will be able to perform the exercises here. If you have a full-height pull-up bar (about head-high or higher), you can use a long towel, two dog leashes, or some other form of makeshift suspension trainer to perform the rowing exercises.
If you cannot do a pull-up:
Shoot for 20 reps per day of each exercise described here. At first, you may only be able to do a few reps at a time. If so, practice this throughout the day. Let’s say, for example, that you can do five total reps of the exercise. Throughout the day do sets of three until the exercise begins to feel easy. Do more reps as you are able but do not go to failure in these sets. Make sure you stop each set with at least one “rep in the tank.” When you can get 20 total reps in two sets or fewer, move to the next exercise.
Start with high angle rows. With the bar or trainers about waist high, stand with your feet below the grips and then walk back until, when you extend your arms completely and your feet remain planted on the ground, your body forms roughly a 45 degree angle with ground. This is an approximation but understand that the higher your head is the easier the exercise is. When you are able to get 20 reps in two or one set, move to medium angle rows. Move your feet closer to the grip so that your body is closer to parallel to the ground when your arms are fully extended. After you have mastered this, move to a position so that your upper body is parallel to the ground when the arms are extended and your knees are bent so that your upper and lower leg form a 45 degree angle. After you have mastered these knees bent rows, extend your legs so that they are straight. Your body should be straight and the backs of your heels on the ground for these rows.
You have now mastered the row and it is time to move to the pull-up. Adjust the grips to roughly chest height, if possible. Stand up while holding the grips; they should be roughly at your arm pits. Lower yourself down while bending at the knee so that you are performing a pull-up with your legs assisting you. Make sure you do not do the majority of the work with your legs. Only assist enough so that you are able to get two or three reps of these assisted pull-ups for starters. Once you are comfortable with the movement and are able to get 20 reps in two sets with minimal assistance from your legs, you are ready to move on to the final exercise.
The negative pull-up is really a let down. Not in the psychological sense but in the physical sense. You start at the end position of a pull-up and then slowly lower your body to the starting position. At first this will not be slow at all. Get yourself into the starting position of the assisted pull-up and then slowly take your feet off the ground while strengthening your hold on the grips. Hold yourself off the ground for as long as you can and then slowly lower yourself under control to the point where your feet touch the ground. Work on slowing this movement and even pausing at the top. Once you are able to get the movement to 10 seconds or more, you are ready to try your first pull-up.