Circular Gallifreyan is the language of the Time Lords in the show Doctor Who. The language I am teaching you isn't exactly like the show, since it is only fan made and translated.

Step 1: Basics

Letters:
Each letter has its own circle. You put each letter on a "word circle". The "word circles" go on "sentence circles", which go onto paragraph circles. Consonants are formed by a stem and a modifier. Vowels are connected to the consonants the follow. Every letter has its own circle, but C. This is because C is either going to sound like S or K, so you just use them instead. Many letters are also a combination of two letters, like TH and SH. If a letter is doubled, then you double the circles too (see later). When reading, you start at 6 o' clock and read counter clockwise.
Numbers:
To create numbers, you want to have one circle for the number, and each number has a concentric ring. Each number is distinguished by how many lines are on the circle. The negatives are denoted by a line in the center. You read the numbers counter clockwise from 6 o' clock, just like letters.
Punctuation:
For punctuation, it starts at the inner circle and radiates out. Also, after each sentence circle, there is a punctuation circle which is normally just a period.

Step 2: Writing Numbers

As an example, I will use the number "-13.37".
To start out, you always want to draw one circle, then branch out from there.
Since its a negative number, the inner circle will have its diameter drawn.
Now you have the negative and 1, the inner circle is the beginning of the number, the outer circle is the end.
Next, draw enough circles for each digit and punctuation, for this number there will be 4 number circles, and one punctuation circle.
The decimal point is represented by a thick circle. A smaller circle in a ring represents a five.

Step 3: Writing Punctuation

Punctuation is one of the easiest parts of writing Circular Gallifreyan. Punctuation is always connected to the inside circle and goes outward. The only time this doesn't apply is when there is an apostrophe. Then it goes from the word circle it is on to the outermost circle.