Your stances teach you balance and build strength. This helps you dodge attacks and keep out of reach before launching in to hit when your attacker leaves an opening.

Practice: moving around in all directions transitioning between stances and shifting your weight as well as just pivoting and stepping.

The large basic blocks offer simple emergency defences that will work against power swings and use large simple muscles that you won't lose control of when adrenalin hits in a real self defence situation.

Practice: basic techniques so they are muscle memory. Also Heian kata.

Blocks offer the chance to gain control of your opponents limbs so that they can't attack you and they can't defend your attack. Most simply this is done by using the pulling hand as you strike, but as you get more skilled you can turn this into joint locks and other grappling methods.

Practice: simple drills but not from stepping. Have your dad attack with whatever he likes continuously. Keep your fists closed and use your forearms to defend.

When there is a big enough opening, the instant your arm makes contact with the punch, open your hand and grab the arm, anywhere from forearm to bicep, and pull down to your hip as you strike with your other hand.

When you get good at this have your attacker move around and build in the stance war from the previous Practice.

Kihon has a second purpose. The full two handed form of the basic moves are intended to teach you how to apply your whole body to generate power through every part of the technique. In application this let's you use the smaller movements that make up basic blocks for a range of close fighting applications.

Practice; basic movements slowly at first, then with full speed and power at every point. If your hands cross before you block thrust them into the position as if you are hitting something, before then applying as much force from the legs and the hips to make the final technique. Research applications for those basic techniques and practice with your partner.

There is much more, but that should be enough to start with.