You can't choose where to place the stress in an individual word, but you can choose where to place the stress in a sentence. It depends on what you’re trying to highlight. Stressing a different word can change the meaning.
Common problems include
stressing too many words in a sentence
not stressing any word clearly
Knowing which words to stress depends on the meaning, context and what you and your listener already knows (shared knowledge).
If you can hear stress in the speech of the person you're talking with, you'll be able to pick up what they think is important too.