3rd Person POV Help? Any Help at All?

I'm usually a first person pov writer. my most current, and longest, novel is in first person but my latest idea i feel like i have to write it in third person pov. but every time i feel like i'm introducing a character wrong. i don't really understand how i'm suppose to describe and introduce my character. do i describe the character and then have another character introduce their name? Do i introduce their name or do i have them introduce their name? Can someone please help me? it's been driving me insane!