HELP HELP HELP ITS HARD
Dude don't panic it's easy, the pronounciation part of Cantonese is probably the easiest part of the language. Writing is where the true complications come in. Sure, Cantonese pronounciation is harder than Mandarin. But Cantonese sounds better, more international and is all round a better language. It's also good for preserving Hong Kong culture.
Here's a cheatsheet of all the tones. All "Si"
Once you master this, you'll be able to read Jyutping and basically most words that are in the tones 1-6. Tones 7-9 are just short or unique tones for specific words.
Here's a video on YouTube that will be able to help with pronounciation.
Does mispronouncing the tones do any bad
Generally yeah, mispronouncing a tone could lead you saying an entire different word. Now weather if you're lucky if you didn't say anything bad is up to what mistake you did. For example cat1 means "seven" but cat6 is a swear word. But if you are a forigner most people will generally forgive or be surprised that you are trying to pick up the language and will be positive and encourage you to learn more.
The normal Cantonese person will not know Jyutping. Jyutping was just created for forigners to get familiar with the language easier. But it does the job on simplifiing tones well. This site has common phrases supplied with Jyutping to make it easy for you to pronounce, writing however is another story.
This is pretty rare and you'd only do this if you are very familiar. But sometimes the same words can have different pronounciations depending on context.
For example the character "行" can be pronounced as hang4 or haang4 to mean "walk or do"
On the other hand, the same character can be pronounced as hong4 to mean a shop/firm/company or a line/row. So it can be very confusing for new speakers.