Hello, everyone!

I woanna tell you about sugar addiction.

Wanna is the slang of want to

Do you like candy, cakes andor other sugary treats?

This sounds more natural

Hello, everyone!

I wonnaant to tell you about sugar addiction.

I'm assuming you were going for the casual "wanna" (wanna is only acceptable in chatspeak in informal settings).

Do you like candy, cakes and other sugary foods?

"Sugars" would be about specific types of sugar. For example, brown sugar and white sugar etc etc.

I like ithem but iI think it's not good for my health (if I eat a lot of sweets) too many sweet foods.¶
What do you think about it?

"I" is capitalized when it's used as a word regardless of where it is in the sentence.
Alternative "I like them but I think it's not good for my health if I eat too many sweet foods." This would add emphasis on consuming too many sweet foods. Also I changed sweets to sweet food because "sweets" by itself is just used to refer to candy- you mentioned cake as well.
Alternative "What do you think about this topic?" but "What do you think?"is ok since you've already established what you're talking about.

I wonnaant to tell you about sugar addiction.

Do you like candy, cakes and other sugary foods?

I like ithese kinds of foods, but iI think it'sthey're not good for my health (if I eat a lot of sweets) ¶
What do you think about itof them?