Building a deck isn't as difficult as it may seem. Once you have worked out a few basic measurements and have all the supplies you need, the rest is pretty straight forward. To work out joist and bearer spacing all you need is a ruler and pencil.
No matter where you live, there will be building codes to observe. Unless you live in an area where there are no building and zoning codes, you will have to abide by your city's rules and ordinances.
Generally on a 10ft x 10ft deck, you will be using a 2 inch. x 8 inch ledger, sometimes referred to as a stringer. The joists will also be 2 inch x 8 inch, 24 inches on centre. This is the general rule if your decking is 3/4 inch thick plywood minimum.
If you are using thinner decking material, your joists should be 16 inches on centre.
The bearer would ideally be 4 inches x 4 inches and support the front of your deck. The footers supporting your bearer would need to be at least 18 inches in the ground in a cement pad to allow for frost heave. Concrete breeze blocks filled with cement can be used on top of your footings to support your actual bearer.