To change the body text, I used Firebug for Firefox to determine that the element to target is the class entry-content.
This means you can change its font attributes by adding some custom CSS like this:
.entry-content {
color: #666;
font-size: 16px;
font-family: Georgia, "Times New Roman", Times, serif;
}
You can use any colour you like.
Don’t edit the theme files directly, otherwise your changes will be overwritten when the theme is updated.
An easy way to add custom CSS like this is to install the Jetpack plugin and activate the Custom CSS module. You could also install a standalone custom CSS plugin, or create a child theme.
Also a heads-up that it looks like you’ve carried over some formatting from an outside program (likely Word or another Microsoft app) since I see this “garbage code” in your browser source:
<!--[if gte mso 9]><xml><br />
<w:WordDocument><br />
<w:View>Normal</w:View><br />
<w:Zoom>0</w:Zoom><br />
<w:Compatibility><br />
<w:BreakWrappedTables/><br />
<w:SnapToGridInCell/><br />
<w:WrapTextWithPunct/><br />
<w:UseAsianBreakRules/><br />
</w:Compatibility><br />
<w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel><br />
</w:WordDocument><br />
</xml><![endif]-->
<p class="MsoNormal">
I suggest you use the Paste from Word button if pasting from Word to remove this code.