Hi J! So sorry to hear about your sister - that must have been very difficult to deal with
A few things that might help while you're getting started:
-I'd recommend starting with calorie counting, because it's free (great if you're on a budget) and it helps you learn more about what your body needs, portion size, etc. I've done WW before, but I always got frustrated with the vague point system, although I know it works for plenty of people.
Sign up for an account on Livestrong.com or Sparkpeople.com (there are other similar sites, but these are the first two that come to mind right now...) - they have tons of tools that will help you determine how many calories you need to eat to lose weight and track the foods you eat.
-Talk to the staff at your gym about putting together an exercise program. Many gyms offer free personal training sessions with each membership, but even if yours doesn't, you might be able to find a staff member who will show you how to use the machines correctly and put together a routine for you. (If not, there's tons of free workout routine sites online - just search Google for some ideas).
Just remember to take it slow - this should be more about slowly incorporating healthy changes into your life than trying to change everything all at once. You'll be way more likely to stick with everything when you focus on making positive changes you can live with.
Good luck - let us know how you're doing