First, lay down with your head turned so that the affected ear opening is downward, pointing to the floor. An old rag will catch the hydrogen peroxide as it drains out. Don't lay on anything you don't want damaged by the peroxide. It will bleach and damage fabric (and other things). Let it all drain back out.
Your best choice is to go to a doctor ASAP because a buildup of ear wax might NOT be your problem, but if you want, you can try this:
A few drops of slightly warm (NOT HOT!!!) mineral oil, followed by a cotton ball to keep it from running down your neck, will help to soften the wax. If you want, you can use room temperature mineral oil, and remove the risk of burning your ear canal. You may need to repeat this once every day for a week, then get an OTC ear cleaner, available at every store that has a pharmacy (lots of grocery, drug and discount stores have them). Get the kind with the bulb syringe, which looks like a small, pointed (hollow) ball. Never use a Q-Tip or other cotton swab in your ear. Use only the bulb syringe and the cleaning solution. That should remove the softened wax. Just follow the package instructions.
Some people just naturally make more ear wax than others. It is not a sign of dirty ears, it's just a natural variation in people. If you are one of those people, you will need to keep the bulb syringe handy, and clean your ears this way once a week, always. You can do it in the shower.
have a family member with this problem