Padding on dining chairs uncomfortable (compressed)
To replace the foam underneath the white cover you have to remove the white cover.
When you just have the wood frame, the first part that is added is the webbing that crosses left / right and forward / back.
Once the webbing is secured, then the foam padding is added and it can be shaped like a curve on the edges or slightly thicker in the middle.
Then there may be an intermediate cover and the final white cover which is secured with the staples. Getting the cover stretched appropriately so that there are no creases takes patience.
Then the base black cover is fitted to hide the staples and edges of the white cover - so that when you grip to pull the chair you don’t feel the edge of the white cover.
This is a project that can be very rewarding.