You will need a modicum of computer knowledge before you start, including a basic understanding of Operating Systems and physical computer hardware. It also essential that you have a good understanding of basic maths and possess a reasonable level of logic. Basic math skills means the ability to confidently perform addition, subtraction, multiplication and division. If attempting to write more complex programs then it may be necessary to develop some higher level math skills.
You will need some programs in order to develop software. The programs needed will depend on which programming language you are learning. Once you've decided on which language you want to learn, you will need to download or purchase an application development program. This will consist of a compiler or interpreter and an editor in which to type and edit your programs.
Last but not least you will need lots of patience and motivation. Patience is required because things very rarely work first time around. Often you will need to review and revise your programming code in order to get it running without errors. When first starting out don't aim too high - try writing some basic programs to start with as this will give you the experience and confidence required to write larger, more complex programs.