Since you are a beginner. I will make it straight forward. Below is extraction of your code. I used internal style sheet. Your example you are using external style sheet.
Using float attribute you can set it to left and right. Here is used float:left to alight one div to left and float:right to alight other one to the right.
Each opened tag has to be closed tag.
<head>
</head>
<!--Internal style sheet-->
<style>
.left{
float:left;
}
.right{
float:right;
}
</style>
<body>
<div id="wrapper" >
<div class="left">
<p class="t0">lorum itsum left</p>
</div>
<div class="right">
<p class="t0">lorum itsum right</p>
</div>
</div>
</body>
</html>
Additional note: If you want to adjust the size of left and right div then use width in style sheet. Refer the updated style sheet below. I made left div width to 80% of the screen width and right width to 20%.(total should be 100%). Adjust accordingly.Background color used to set the background color of the div.
.left{
float:left;
background-color:powderblue;
width:80%;
}
.right{
float:right;
width:20%;
background-color:yellow;
}