Theme help.

I searched and couldn’t find a answer that helped. I created a site in HTML with 3 rows and 3 columns. I successfully converted my HTMl5 code to wordpress. Now I’ve ran into a problem when it comes to implementing the loop(s). I have 3 rows with 3 columns each. I want to display on the homepage three categories in these rows.

Category one
[1] [2] [3]

Category Two
[1] [2] [3]

Category Three
[1] [2] [3]

I would also like to add that I have more than three categories, but would only like to display these three on the homepage and exclude the others. I would appreciate any help on how to go about this if it’s possible.

Thank Yuu