There are many places for a player to get supplies and help, I will list a few sites and locations that i use when looking for help/supplies.
Deckstats- Deck stats is a good website for new and continuing players. This website allows you to build, save, and search for decks. These decks are made by fellow players and can give some insight into deck building. This site is good because it helps you with deckbuilding by showing you how your deck is balanced and if its legal for tournament or standard forms of play. This site also allows one to buy decks they like or one they build on the site for a relatively decent price.
Youtube- Youtube is a great resource for starting players to learn MAGIC.