Yeah the coaching lessons are rather expensive. But I think if I practice a lot by myself reading and practising tennis techniques I could find good techniques over time? I just tried a hour for different grips, if I use eastern the balls go more to the sky (like sereval meters over the backline) , or if I use western the balls go to net or just slightly over the net and don't go over much. But I guess this is wrong way to hit, the topspin forehand should go lot over the net and then drop fast to court. But there isn't any specific grip for forehand topsin? Somewhere I read that one should use Eastern grip for this. Another thing I would like to know is that could my very bounching racket net be responsible for these long hits? I have played for long with this racket and in the past I have mainly used only my hand (WRONG) to create the power with so the balls stayed in the court.
The eastern grip is a good grip for a beginner, I learnt using that grip and switched to semi-western last year. I wouldn't recommend using a western grip unless you have a coach as it's a pretty advanced technique. Try eastern or semi-western for now.
I'm not really sure how else to advise you. Maybe you're pushing the racquet forward with your swing rather than whipping it up and behind the ball? Just practice for 20 minutes brushing your racquet behind the ball, it doesn't matter if it goes really high over the net - just get used to the sensation of applying topspin and the effect it has on the ball.
As for your racquet, perhaps you have it strung too loosely? This would explain it flying long, or it could just be your technique causing this. A good beginners racquet should be around 10-11 ounces, head size 100-110 cm2 and strung to a medium tension (around 55 pounds). I know there are racquet experts on this forum so they'll be able to advise you better than I can on this though.