Planning the front yard

So I've been thinking a lot about what I want to do this year in the front. We're going to actually get to plant things since those trees are gone, and now this year we won't be THOSE neighbors... I hope.

I put together a rough mockup of our front yard online:

You may notice that we don't actually have that little brick walk at the front stoop... YET. We want to install one, and since the space is seriously less then 6 sq feet, it may happen this year. It may.

The edge I'd like to do petunias. They are easy, cheap, and fill in nicely. And given that I'm still new to landscaping and such I don't want to try to bite off more than I can chew.

The blue thing in there, I'm not sure what I'm going to do yet, but there and in any open spaces I'd like to put something low as filler to compliment the petunias. Possibly dianthus or silver artemisia.

In the back is the part I'm most excited about. I'd like to grow zinnias. I'm a little nervous because I've never grown anything from seed, but apparently they are super easy. Also I want something taller in front of the lower level window. Anyone have any advice for a novice landscaper?