Threading on the machine

Question

A bought this machine from a friend and I never had a chance to work on it for about a year. When I did it kept messing up and acting like it was catching on something when the needle went down. Took the fabric out and there is a glob of mess of thread. I worked and worked threading the machine, but nothing worked. A lady from a quit place came down and said it was threaded wrong and it worked great for her when she tested on a small piece of matrial. I just got done working on something and ran out of the bobbin thread and had to redo it and now it's messed up. Like I said I don't have a manuel for this machine. Can you help me.