I've been a motorcycle rider for almost six years now ... but that entire time was spent on the same bike that I purchased new in 1999 (a '99 BMW R1100R w/ ABS). Each winter I would put the bike to bed in the garage with a YUSA trickle charger with float control ... but unfortunately this season the bike wouldn't start. There seems to be just enough charge in the battery to keep the analog clock running - but not enough to get it to turn over.
I may not be the most mechanical guy ... but I'm pretty sure this means its time for me to get a new battery.

Since I've had this bike since it was new (and when I was new to motorcycles) I've obviously never had to replace my battery. In the past, for oil changes and getting new tires - I would have a dealer do the work or installation. Obviously now, the bike won't start so I can't ride it to the dealer.
What suggestions would you have for a non-mechanical guy on what to buy and how to get a new battery ready to install, fully charged, and back in my bike so I can get back out on the road in what is always a short summer in Buffalo?
Thanks for your help!