Getting the Bobbin threaded in the Machine

Question

I did it once and had it working fine, now when I'm doing it thread piles up and when sewing a little it james up and extra thread starts coming out all waded up. help? I do not know where my owners manual is & I am not sure this is a Kenmore Drop-In Bobbin 16231. I do have the model number and serial number. Please helpI have a aewing machine from Ken more and it is called Jaguar quick sytem it is very old and inherited some time ago and have never used it. The model # is 158. 1070180 and cannot find and instruction manual for it.  I have tried to thread it today and the bobbin will not thread no matter what I have tried.  I have tried to clean it ect. I t comes in a wicker basket and would like to get it to work.  I have used several other sewing machines and never had this problem before.  Can you help me?