Once you're able to make your own Objects and Shapes, you'll need to know how to color both their Fill and Stroke.
To get us started, make an Ellipse object.
At the bottom of your Inkscape program, you'll see a horizontal list of colors.
You can Scroll through this list to see various color options.
Select your Ellipse.
Then Left-Click on one of these colors.
Your object's Fill Color will change to the color you chose.
To change the Stroke Color instead just 'SHIFT' + 'Left-Click' on a color.
And your object's Stroke Color will change.
This is the basic way of changing Colors.
To start with more specific Color changes, open up the Fill and Stroke window.
To open this use 'SHIFT' + 'CTRL' + 'F'.
With nothing Selected you'll see this.
If you Select your Ellipse more options will appear.
With your Object still selected, make sure you're in the Fill tab. You'll be there by Default.
Clicking on the 'X' or No Paint will remove the object's Fill Color.
Clicking on Flat Color will give us what we started with.
There's also the option for a Linear Gradient.
As well as Radial Gradient.
Once you've chosen your Color, you can start Adjusting how it looks.
You'll notice 5 different tabs for Color Adjusting.
RGB, HSL, CMYK, Wheel, and CMS.
Under any of these tabs, you can change the Alpha of your color, also known as it's Transparency.
In the HSL tab, you can easily set the Lightness of the color.
This is an easy way for getting Lighter and Darker shades of your chosen color.
At the bottom of the Fill and Stroke window, you'll see Blur and Opacity.
This will turn the entire object Blurry and set it's entire Transparency.
If you were to select the Stroke paint tab, the options are all the same, but will only change the Stroke of your object.
Let's move on to the Stroke style tab.
Here you can change the Width of the stroke.
You can also change the Stroke type using the Dashes option.
Use this option to change your Stroke to other types like Dashes as seen below.
Select your Ellipse and give it a Linear Gradient.
Then choose the Gradient Tool.
With this tool Selected, we can adjust the gradient's handles, to change the way it performs.
With a Radial Gradient, it will have different handles, but it can be adjusted the same way.
The last thing I want to mention is choosing a Primary and Secondary color for your gradient.
This can be tricky, so I'll show you an easy way to mimic the result.
As you can see, when you set a Linear Gradient your Primary color fades into 100% Transparent.
To mimic a Secondary color, Duplicate the object you want to use the Gradient on.
Then set it's Fill Color to your choice of color.
Lower (PageDown key) the duplicate just behind the original Object.
Now your gradient will use the Primary color and fade into the Secondary color you chose for the duplicate.
(This tutorial may continue to be updated!)