Investing in real estate through buying a primary residence can be a great way to start building a real estate portfolio. Here's a step-by-step guide on how a beginning investor can start investing in real estate by buying a primary residence home a year for 10 years:

1. Determine your budget: As a beginning investor, it's important to determine your budget and how much you can afford to spend on a home. This will help you to narrow down your search and ensure that you're not overstretching your finances.

2. Research the market: Once you have your budget in mind, research the real estate market in the area where you plan to buy. Look at factors such as average home prices, rental rates, and vacancy rates to help you identify areas that have strong potential for rental income and appreciation.

3. Find a suitable property: Look for properties that are within your budget and have good rental potential. Consider factors such as location, size, and condition when making your selection.

4. Secure financing: Once you've found a suitable property, secure financing through a mortgage lender. Be sure to shop around for the best interest rates and terms.

5. Purchase the property: Close on the property and move in. Make any necessary repairs or upgrades to the property to increase its value and rental potential.

6. Rent out the property: Once you've made any necessary repairs or upgrades, list the property for rent. Set the rental price at or above the market rate to ensure that you're earning a profit.

7. Repeat the process: After a year or two, repeat the process by purchasing another primary residence home. Continue this process for 10 years, buying one property each year.

By the end of 10 years, you will have accumulated a portfolio of 10 rental properties, which will provide you with a steady stream of rental income. The exact amount of cash flow you earn will depend on a variety of factors, such as the rental rates in your area, the condition of your properties, and any expenses associated with managing the properties.

Over time, your rental income will compound as you continue to rent out your properties and increase the rent rates as the market allows. As your properties appreciate in value, you may also consider selling some of them for a profit, further increasing your cash flow.

Overall, buying a primary residence home a year for 10 years is a great way for a beginning investor to start building a real estate portfolio and earning passive income.