On this page is how to speak Halq'em ylem, or at least it might give you an idea of how to speak it. Some words have several stressed vowels. The stress marks are needed to tell which part of the word is said louder and higher. Without this a speaker will have a foreign accent or say the wrong word. Stress means the vowel is pronounced fairly loud and with a higher melody than if the vowel was unstressed.
High stress has the highest pitch, about four notes above a vowel without a stress mark.
These are popped consonants. These sounds are made by raising the tongue to narrow the passage of air till you hear the friction of the air. But instead of using your voice you just blow air and it produces a friction sound between the middle of the tongue and the front of the hard palate.