Allright, many people think ms paint is a terrible, cheap program.
No, its not terrible. It just needs some taking time to.
And like, MS paint can give off some pretty effects.
And here, i'll tell you how to do hair in Paint.
What You'll Need:
Paint - ;D
Drawing Skills - If you can only draw stick people, then your going to not be that good at hair.
A Nice Mouse - I use a tablet. x3 But a mouse, along with a careful hand, and you should do fine.
So, let's get started. First off, we needa a base. I'mma just grab a base from tektek, with eyes, and paste it in paint.
Make sure to save alot, and make your canvas roomy and nice.
A good idea; so you don't have to zoom in alot, go to View > Zoom > Thumbnail
It will show what your canvas looks like, and so, you can fix a problem without clicking the zoom out / in a million times.
Now, let's get started.
Here's my base.

First off, grab a color. It can be any color. Make one up, or grab one from the color palette in paint. (I don't suggest it though, I'd rather you pick a nice, natural color from the Color Picker. To get their, simple go to edit under colors on the top menu.)
I want a nice brown. So, i got my brown.
Draw the outline of the hair, and fill it in with that color.
(When drawing and shading, Aero zooms into 8x or 10x)

Now, we start shading. Using the color editor, pick a slightly darker color.
Now, a common mistake made by ms painters if that they think they need to draw every strand in. Yes, you draw strands, but not with the highlights. leave the strand and details up to the highlights.
Anyways, start shading at the roots and where shadows would fall.
And define some chunks of hair

And keep doing this, using darker and darker colors.
And here is my outcome.

You may think it looks a little weird now, but we're only half done.
Now, grab your base color for you hair, and then pick a lighter color then it in the color editor.
Start drawing in the highlights, and make them have long streaks in them, as to say their are strands.
Like this ;

And highlight more and more, to where your only doing dots.
Here's my finished product of highlight shading.

I made the highlights bigger and more defined.
Allright, let's start blending those shadows more. Choose a color a very very slightly lighter color, and draw between every shadow.
Here is what i mean.
It may be hard to tell, but we just added some more colors between the shadows, to blend more.

See? We've added more colors. :'D We're nearly done.
If you wish, you can add some random strands here and there.
Even add some shadows under the hair.
If not. your done. ;D
Stick a signature on it, save it, preferably under .png, and yay! Hair in Paint

Any questions? feel free to ask. ;D