Welcome Gael and beautiful calico girl!
THANKS for adopting and THANKS for spaying an adult cat!
Not only will you receive far more than you could give
, you are making a positive difference in the life of someone whose chances of being adopted are not as great as with a kitten. You should be proud of yourself!
The forums here are wonderfully informative regarding "Cat Care 101". Check those out! And I'm sure there are a lot of us who are willing and able to help.
Basically, you're doing the most important things -- adopting and spaying/checkup/innoculations -- already. You know you'll need good quality cat food (premium is best and actually cheaper as it keeps your cat healthier and cuts down on medical bills) from Petco, PetsMart, or other "Pet" supply store (Nutro Max Cat is a very good brand; other good ones include Natural Balance, Optimum Nature's Recipe, PetGuard, PetGold, ProPlan, Triumph, and Trader Joe's if you have those there, sells premium cat foods) (wet and dry is good), fresh water daily, cat furniture, scratching post(s) and pad(s), a large, sturdy litter box and I recommend "scoopable" clay litter, well-made, safe toys, and I like to give treats, too, such as Whiskas Temptations, Nutro Max Cat, Whisker Lickin's, or other), and if you aren't planning on her sleeping with you, a nice, soft, washable cat bed (Petco has berber "cat donuts" for around $10.00). A sturdy plastic cat carrier is also recommended for vet visits and/or any other travelling; all of the above are available at the referenced stores. And I like a breakaway collar with a metal ID tag on each of "my" cats. Microchipping is also a good idea; this is something to ask your vet about.
BEST of luck and can't wait to see pictures and hear stories!