jump starting an elise s1

[Motorsport3]

Haven't driven my elise for a while now and went to the garage to start it today but battery is flat...Never jump started a car before and having watched some youtube videos looks pretty simple.

One question I've got is whether any car can be used to start an elise?
As per my profile I've got a bmw which Im pretty sure has a different battery (same voltage though different amp, i think). Can I connect the two?