I have 2 2003 GTI's I have had them out a few times this year one of them suddenly won't start. I went to start it it did turnover and then die which it normally does but when I pressed start again instead of starting it just works the starter. It doesn't seem to be firing at all.

Also I tried so much I think the battery is low what is the best way to charge it? I assume I can't use my car charger. Sorry I'm a computer programmer AKA geek so I'm a idiot when it comes to mechanical stuff.

Thanks for your suggestions!!!