50 LED lights installment / power supply and resistors help

Hello guys,

I am having some trouble with my LED lights. I am thinking to solder about 50 LED lights (3V, 20MA, 5mm each) and install them to my keyboard. I was thinking to use my keyboard's card but seems like it does not give enough power. I have tried with one LED light bulb, it worked fine but after I solder 2 together, it seemed like it lost its power about half. So If I go over 2, it wont work. I am looking for some resistors and power supplies to fix this problem but I am not sure what volt to choose for the power supply and what resister to choose. Can some one help me please?

Do I have to use resistors or just a parallel wiring should be ok? Can I use a computer's power supply or would it be too much?

Thank you,

 

Thank you, I will check it now.