What is the best way to use concrete and stepping stones for a garden?

Your garden is lovely. Check out "Paver molds" on Amazon for inspiration. You will have to play around with them to incorporate your already existing pavers.

One important consideration as we get older is to make sure that outdoor surfaces won't be slippery to walk on. Another important factor is that we may need a hand rail, if not now, then soon. You want to be able to enjoy your yard safely for many years to come. With your back problems, you may want to hire someone to do any work that requires lifting, bending or twisting.

Your garden looks lovely. However, a path will have to be dug out (about 1" or so depending on the stones you're using. Then lay a paver sand and make sure you tamp it down so the stones will have a fir base or they will shift. Lay your stones (hopefully they're flat) and then add some more paver sand. Hopefully it will keep any weeds from growing. If you have a bad back, have some one else do it. If your back doesn't give out, your knees may. Good luck.

To put your current round pavers into concrete, I would remove any material around them, if sand or smaller rock maybe use a shop vac, then mix and put in the concrete. Good luck.

Taunya I am not sure why you want to set them in concrete. They look good from this photo. I have a "paver floor" on my bottom patio with sand between them. For years I doctored a concrete pad there but with our crazy weather it kept cracking. You could go with a pea gravel between the stones that way when they shift you can adjust. I am too a 60 something with back problems but I work like a 20 year old in spite of it just to show the "youngsters" I can do it. You go girl!

Check YouTube for some ideas. https://www.youtube.com/results?search_query=easy+pathway+ideas

Use mulch!

You can use special plantings around the stones like mosses that will help keep the stones in place better & year after year it will improve as the pavers settle & the plantings grow more around them. My paver patio has been a continuation project for about 5 years!