My teacher wants me to make my own business plan about a dog supplies, and i dont know how to do it. =\

Ask yourself:
What is my product? (obviously dog supplies)
What is my product portfolio?
Who are my customers?
Who are my suppliers?
How much starting captital do I need?
How do I finance it?
What are my recurring costs?
Do I need employees?
Do I need licenses?
Do I need to register for a fictitious name?
Will I run it as a sole proprietor ship or as a a corporation?
How will people learn about my store?
How long will it take for my store to return a profit?
Who is my competition?
Why should customers buy from me instead of them?
What are my strengths, weakness, opportunities and threats?
What is my mission statement?

You answer those question in an essay format and you got yourself a business plan.