The problem you face is normal and common. In fact getting sound from the instrument is the fist step of many you will have to accomplish.
Do the following:
- take the headjoint (J) out (the part with the blowing hole).
- Hold it with your left hand and and blow into the blowing hole (with the HJ separated from the flute body) as you would blow on a bottle to make it sing. Try different positions of your lips but the idea is to produce a jet of air focused on the hole (or most precisely on the facing edge of the hole, but this will come later as you adjust to get the best sound.
- Once you have it, close the open end of the HJ with your right hand palm. The sound will increase in pitch,
Play with this for a few minutes
Once you can produce sound reliably, insert the HJ fully on the flute body and repeat your blowing until you get sound. For this, some notes are much easier than others, I recommend you close all the keys of the left hand and leave those of the right hand open. You should produce a G in that position.
Now if you cannot afford a teacher you need at least a book with the basics of the instrument. But the first step is of course to be able to produce the sound.
End lesson one...