Also, about how much does it cost for a bag? Can I get it at Walmart?

You can spread it with gloved hands no probelm but if you have a big yard it might take a while and the price varies depending on what brand and type of fertilizer you are looking for really.

You may attempt it, but, IT IS IMPOSSIBLE to ensure a uniform/even application of the fertilizer.

A inexpensive spreader is easy to find.

"Drop" spreaders apply materials in a well defined, straight path, with the fertilizer dropping directly down from the hopper. They are more precise, and are the best choice if you have adjacent areas you wish to not treat( such as gardens, pools, etc., but due to the small application area, it will take longer to fertilize.

"Broadcast or rotary" spreaders have a spinning disc at the base of the hopper that throws the materials in a wide, fan shaped swath in front of the spreader. This treats large areas quickly, and helps prevent "striping" which is a very common problem with inexperienced use of drop spreaders.

As for the recommendation of using a triple thirteen fert., it is at best a starter fertilizer for desirable turfgrasses. Any home and garden place will have suitable products available, I'm not sure where you are but Lesco and Hummerts are the places around here.

Cost depends on the brand you buy. A spreader will give a more even distribution. I have used the hand-held grass seeder from Walmart that is made by Scotts. Works fine. Don't handle the fertilizer with bare hands.