Blane McDougall could be trained if you wish, although you can pick up someone with the same potential but 10-15 more skill points very cheaply. The other players aren't worth anything due to their skills and/or low potential.
In my signature there's a link to a beginner guide I wrote a few seasons back when I was starting out. There is a section on training which provides some information and outlines a plan you could follow. It's not a detailed guide but tries to cover some basics.
One of the easiest mistakes to make early on is spending too much in the transfer market. So if you see a trainee you might like but aren't sure if they have the right skills, or if they are too expensive, feel free to ask here or in the discord. Ask as many questions as you want, I know there's a lot to learn when you're starting out.