Must admit it took a bit for me to learn how to play "Defend your castle". I had no idea how to get archers. I kept saving money to buy the archers and had no idea how to get a convert. Finally solved that mystery, buy a temple.
First purchase a temple, then you can drop guys right in the MIDDLE of the courtyard of your castle. You can only convert one at a time. If you drop one while the other is being converted you will be dropping him to his death or on your doorstep.
When you get enough money you can add the mana pool, workshop, etc. This will give it a flag on one of the towers of your castle. Click the flag to add them to that type of skill you want.
You can lose converts by getting beat on or by not paying the upkeep on them.
Once you think you have the hang of it, now it seems to get easy for a few levels. Just assign converts to skills and it will all be ok, right? Wrong..... Super stick guys come out and are bigger than your castle. Upgrades and your workshop should help with this. You can click on him to pick him up but it only knocks him down.
I am no expert on the game by a long shot but I saw that some wanted to know how to use the stuff so I posted. Maybe we can topple some scores now.