Series is a better way of charging - each cell is being monitored. If you have a low powered charger (say 4s/5amp) you will both balance faster and can charge twice as fast with series. BUT
And this is a big BUT
Connect a series plug wrong and you get smoke and a damaged lipo. Connect a parallel plug wrong, you only get a fried balance lead. Parallel is much easier (and safer) to set up.
Get a 20+ amp charger, so you dont need to worry about series charging. Then dont do it till you have a better understanding of how lipos charge.