String in UTF-8 format was inserted to DB as ???????????

Question

I get string in UTF-8 format, and when I insert this string to DB it's appears as ??????
I know that string are in UTF-16 and I need to convert it to UTF-8.
I search in web to find good example but i don't find.
Someone can post some code or link how to convert simple string to string in UTF-8 ?

this is example of string in UTF-8 that i want to insert to DB.

Str= "œæÆ à â ç é è ê ë î ï ô û ù ü ÿ ";