New to PLEX and have question about extensions on streams

Hi, I just installed IPTV on my Windows 10 PLEX and have a USA list of channels and an Int'l list. 1) Now that I have these list, where do I put them so that IPTV will see them? 2) Do I give each a name? 3) some of the http listings have different extensions, i.e., m3u, m3u8. Can IPTV play both of them? Some items on the list start with rtmp: instead of http: some have mms: Do these things make any difference to IPTV? Any help would be appreciated. Thank you
Carlos