For your bobbin, thread it and hold it by the thread only. If the bobbin stays in place and does not slide down, then the bobbin is okay. If when holding the thread only, the bobbin starts sliding down, then you have to adjust the little screw on the bobbin itself, turning the screw only 1/4 turn.
If the needle is in right, and all the way, and you have it threaded correctly, turn the wheel and bring up the bobbin thread. Then take a piece of cotton material, double it, and sew some stitches. If the bobbin thread is on the top, the bobbin is too loose. If the top thread is on the bottom, the tension on top is too loose. Both threads should meet in the middle of the fabric for correct sewing. I hope I have this right, it is getting late in the evening for me. Good luck.