Where?
Navigate yourself to "Ultimate Team" and into the "Play" tab. Select "Squad Building Challenges".
How?
The easiest method in my opinion is to finish the tutorial/base tasks.
There should be 8 in total (These tasks need less players). I you haven't got the correct players to swap just look at the transfer market and set your filter to "Instant Buy: Price max. 200-250".
After doing so there are two more SBCs to finish.
Just go to the "Upgrades" and swap players you do not want/need. The position of the players doesn't matter!
Personally I swapped two teams of bronze which I still had.
What about the other game version?
As I wanted to do some tasks for the other version the achievement popped right BEFORE doing one tasks. I guess they will unlock automatically without doing anything more.
Attention!
SBCs via the "FIFA FUT"-App (FIFA companion) do NOT count!