(just want to mention, that you can play either from the front, left or right side, depending on how you feel most comfortable).

Now, when you blow into the Didgeridoo you have to keep your lips very lose. Almost as if you say "ffffffffffffff".
Most people, when they try first, get a sound that sounds like a toot.

When you get a clear sound out of it, the next thing too try is to play overtones.
You can do this in 2 ways.
One is to say (without sound)"You" and "We".
The other is to move your tongue like when you whistle.

Try also the vowels: a (like the "u" in but), e (like the "e" in ever), i (like the "ee" in cheese), o (like "oh") and u (like "oo" in food)

So you can in a way play a Melody with overtones.

Now the next thing is the Circular Breathing

Basically you do 2 different thing at the same time.
One is breathing in to your nose.
The other is pressing air out of your mouth using your tongue and cheeks.

Most people learn to do it with their cheeks.
In my eyes it is much easier to do it with the tongue, because you can control it in many ways.

One hint I can give you is:
You open up again (to blow air into the Didgeridoo) by making the sound of a "K" (without using your voice).

Imagine, that instead of pressing air into the didgeridoo, press it back into your mouth!
You push it in a way against the back of your mouth and so it takes more time for the air to come out of your mouth, which gives you more time to breath in!

The consonants which are mostly used for Rythm are:

"k" or "g" (when you open up after doing the circular breathing)
"t" or "d" (tip of the tounge)