You literally just go into your project Preferences > head to Maps&Modes and see the DefaultGameMode there…
And right below it… SelectedGameMode as Collapseable List… just… unfold it… And place your Character into the DefaultPawn Slot, instead of the DefaultPawn Object.
Okay… I found Beginner tutorials in English, German, Russian, French, Spanish, Arab, Egyptian… I even found some in Swahili 
So… I think there might be some tuts for you to go…
It´s just that most of your Questions are really the utterly fundamental basics of working with the Engine… The Particle Stuff aside, cause this is something you shouldn´t touch right now, when still dealing with the simple Problems of placing an actor or even just drop the Default Pawn