Please note that the language in the following answer includes the situation where a defendant represents himself or herself. It is very rare however, for a defendant to go trial without a lawyer because trials are complex and the potential consequences of being found guilty are serious.  

Before the trial starts, the lawyers (or the defendant) choose a jury. The process for picking a jury is called "voir dire" (pronounced “vwuah deer”) and during the voir dire, the judge and both sides ask questions of the potential jurors to make sure the jurors will be fair and impartial.

Before the evidence is presented, both sides have a right to give an opening statement outlining the evidence.  

During the trial, the lawyers (or defendant without a lawyer) present evidence through witnesses who testify about what they saw, heard or know and sometimes through documents and other evidence that can be used at trials. The lawyers (or the defendant without a lawyer) elicit this evidence by asking the witnesses questions. Witnesses may not simply tell their story without being guided through the testimony by the lawyers’ questions. After all the evidence is presented, the lawyers (or defendant without a lawyer) give their closing arguments. Finally, the jury decides if the defendant is guilty or not guilty or if there is no jury, a judge will decide. The jury must be unanimous in deciding that the defendant is guilty beyond a reasonable doubt.