Tips needed on concreting swing posts into to lawn
we'll need to first poor concrete to stand the post on and then fill the rest of the hole with soil.


The best solution is to dig the holes, fill the bottom with a foot of gravel for the post to stand on,  put the posts in place and then concrete around the post. Water running down the post can drain into the gravel.

If you stand a wooden post on concrete it will rot quickly. 

I would use pressure-treated timber (or a species that is rot-resistant).
I would check it annually for rot and expect to replace it in 10 years.