Zone 3a is quite cold and your choices should be limited (a good thing for newbies).
My wife and I are also very new to gardening. This is what we did:

(1) Have a walk around the neighborhood, or visit local nurseries and garden centres (use google map for listings) to see which plants we think are beautiful. Record the names.

(2) Research on an online plant search engine such as:
http://plants.ritchiefeed.com/NetPS-Engine.asp?31090003

It is better to go with low-maintanance (little pruning required), grow-on-any-soil & pH, disease-resistant, non-invasive, inexpensive, and long-lived shrubs for starters. So even if you make many mistakes (like we did), your shrub will still survive.

(3) There are already a good selection of popular shrubs from Rona, Canadian Tire, and Home Depot. Their prices are usually about 60% of what you pay at a nursery. But they don't carry rarer plants. Choose the plant that is the most virgorous (green) and with a good form (strong centre, branches not crowded). You will also need to buy a few bags black soil / garden earth and mulch.

Mulch makes a huge difference in visual appeal. If you wish to quickly impress your neighbor, try red-dyed cedar mulch. (But they will pay more attention to your mulch than to your plants.)

(4) Follow an online planting guide of container plants. Loosening the roots (cut the encircling roots if necessary).

(5) For more visual appeal, you may consider retaining wall stones. You can use them to make the border of your garden. Rona carries them.

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If you wish to have a quick recommendation, we recently get a "salix integra Hakuro Nishiki (dappled willow Hakuro Nishiki)". This medium-sized shrub puts on pink & white new leaves in the spring and early summer, looking like a star burst to all directions. Very impressive. We got one from Canadian Tire for $14. Planted it just before the heat wave, which did nothing to it (no withering).

I also recommend "Thuja occidentalis Little Giant (white cedar Little Giant)". These are evergreen shrubs that will grow into individual 2' green spheres. You can use them as the backdrop along your house. We got the 1-gallon from Canadian Tire for $6 each.

Yet another recommendation is "Rhus typhina 'Laciniata' (cutleaf staghorn sumac)". This medium shrub comes from the regular staghorn sumac, which is often seen along highways. The leaves turn into very beautiful red in the Fall. The shrub grows quite aggressively.

daniel - Thank you so much! This is wonderful! I am armed with all sorts of ideas now. Thanks again!