Number of Products Across

Can anyone guide me to where I could change the number of product(s) across the home page, right now I have 4 products
across I would to change that to 3 product across so that I can make the product image(s) bigger.
Thank You

You can use the Featured Products module and limit the product number to 3.
Likewise you can use the Latest products module as well limit product number to 3.

Go to admin >> Extensions>> Modules << edit either featured or the latest and Add module and insert 3 to the limit input box.

Hope this help u