if you know how to do relational framework part. Then you have the n-back explanation:
In the less or more operation the app select the maximus element (in the upper example (2) pencil) . in the same/opposite operation if is the green color word is the same as the last element the app select the green word else the last element of the chain is selected (in the upper example (1) the App selects cat) noTime: Use the app without time limitations
In the case of relational framework n-back I think that my mental processing speed is slow (i do not practice very much this training) i can not answer in less than 4 second therefore i do not know if is this training a good working memory training. If you can process a relational framework in or 3 i think you can do a working memory training.
I think you can improve your focus and mental visualization with The loci method and with faces and names memorization