Soil type? Exposure? What zone are you in? How much time do you have for gardening and upkeep/maintenance?

I'm not sure what the soil type would be, its just some topsoil the local landscaper brought in. I was considering mixing in some triple mix soil with it if that would benefit the plants at all. It would be a southern exposure, seems to get sun all day. I guess my zone would be like 6a? I'm in southern Ontario. As for time, I could easily dedicate a couple hours a week to gardening, more or less if needed. This is my first garden project so not really sure how much could/should be dedicated to the gardens.

With new construction, chances are the soil is in pretty bad shape. The deeper layers of fill soil get dug up, and then, once construction is done, they toss some topsoil down and call it a day. So your first task would be to lay out the area you want for your bed(s) and start working on amending the soil. If I were you, I would just work in lots of organic material and then cover the area with some wetted down cardboard to keep the weeds suppressed. Then I'd concentrate on all the stuff people do when they first move into a new home. Spend the fall and the winter reading up on garden design, think about what kind of plants you want and which ones would work for your zone, sunlight, and space, and then you'll be ready to go next spring.

Ditto jnavarro31's comments + use recycled BROWN cardboard (try cartons from a bike shop) to suppress weeds. Worms LOVE cardboard and you want worms in your soil. They poop and that's better fertilizer than any chemical ever dreamed of being. Avoid chemical fertilizers--they're toxic. Organic seaweed extract is the only "supplement" I use for my annuals & perennials.

You need to identify which direction the house faces. Mine faces east and is square with the compass so I know where there's sun vs. shade. Some plants/shrubs thrive in one or the other so do your homework when selecting plants if you want them to grow well in your garden beds.

Soil is important and chances are yours is builder's gravel or worse. It will take years to improve it but with diligence it can be done. I'm lucky; my parents practiced organic gardening for 40+ years before I moved here. My soil is slightly acidic sandy loam and I give thanks for it every day.

Think about what pleases your eye; visit a nearby botanical garden. I decided when I moved here I didn't want rectangular beds so all mine (yes, I have quite a few) curve. I borrowed books from the library and read up on perennials/shrubs that are hardy in my USDA hardiness zone. My garden beds are well established with plants that begin blooming in March and others that begin blooming in October.