advice on lipo batteries and charger please

[autonm]

Im new to all this lipo stuff Last time (about 10+ years) ago - to charge was simply connect the battery up and turn the timer on for 25minutes.

But im getting back into racing, and just bought a fancy new CORE UDC-20 charger along with a saddle pack of Lipo 3.7V 4200mAh 30c

SO - anyone with a CORE UDC-20 charger tell me (except for choosing lipo) what settings I should be using on the charger?

Is it as simple as choosing AUTO - or set it up for 4.2A and 7.4(2cells) ?

Also how do I know when the batteries are charged? Will it stop itself? or is it when the current charge (amps) is close to 0 ?

thanks