If you have more than one character in your story you will have to write dialogue. Even with just one character dialogue is possible. One of my favourite resources on dialogue is Dave King's Self-Editing for Writers. Actually, it's a terrific book all round.
Here's a brief dialogue.
"Ayyoop, them stars shur is purty tonight," said the grizzled old cowboy.
"Bah!" Bob snapped whitheringly, "Stars are just gas, like some people I could name."
"Sorry," said Cookie as he let loose another fecund cloud of gas. "Beans always gets to me."
"Then why does you only cook beans?" Stan coughed. The fire burned blue as the three men held their breath. "Is that there star gettin' bigger?"
Wait a minute, three men? I was sure there were four. The problem is that Stan and the old grizzeled cowboy are the same person. It's important in dialogue to keep the attribution consistent. If you are having an old grizzled cowboy talking, then he needs to stay an old grizzled cowboy through the whole dialog...