The font tag (<font>) can take several parameters, among them color and size. Most browsers recognize a few standard color names -- red, blue, green, black, white, &c. -- but you're best off specifying the hexadecimal number of the font color you want. Fancy graphics programs will tell you what this is, and there are online references like this one that help you. Just pick a color you want -- red is ff0000, for example -- and specify it in the font tag. Thus this:

<font color=ff0000>this is in red!</font>

You can also tell you fonts what size to be, either by using headline tags or by just giving relative font sizes. Headline tags are really easy:

really big text	<h1> </h1>
pretty big text	<h2> </h2>
sorta big text	<h3> </h3>

Font sizes are parameters in tags, like color. You can specify relative sizes by saying "plus or minus this much," like this:

<font size=+2>this is two sizes bigger</font>
whereas
<font size=-2>this is two sizes smaller!</font>

Which renders like this: this is two sizes bigger whereas this is two sizes smaller!

You can of cousre combine font sizes and colors:

<font size=+2>this is two sizes bigger <font color=ff0000>and red</font></font>
whereas
<font size=-2 color=33cc00>this is two sizes smaller and green!</font>

Which renders like this: this is two sizes bigger and red whereas this is two sizes smaller and green!

(Notice that you need a closing font tag for every tag you begin.)