LED kit went wrong any electrically minded people please. help?

I have soem of the parts left an led box with 2 off 1.5 volt batteries I have bouught a 5 amp connector block and a quantity of fast and slow rainbow LEd's 5mm. What is the minimum /maximum to attach via the connector block any help gratefully received. The connectors that came with the kit didn't work idnt work as they broke and I am no t good enough at soldering and maybe using wrong sized soldering iron