So, I'm going to give a very basic explanation of the writing, but first I want to show you the source of this gallifreyan alphabet:

Gallifreyan - shermansplanet

Loren Sherman managed to create a great looking alphabet, that I'm happy to have found. The instructions in the guide are very, very clear. For those of you who just want to use a translator:

Translator

When writing circular gallifreyan, you start at the bottom and write anti-clockwise. Start by drawing a small circle. Next, add your first letter. The diagram for consonants is really clear, so no further tips on that, when writing vowels however I would recommend using this extended sheet: vowels.

The following letters are added the same way, going anti-clockwise in your circle. When starting a new word, you also start a new circle. Circles can look more joined by the empty shape created by the letters T, SH, R, S, V and W.

When all the words have been written, they are surrounded by a circle, which is surrounded by the outer circle. The lines go on until this outer circle is reached.