[KamaalJema]

does it look like they just can't establish connection to the server? well if it is it probably means your ip isn't private and/or ports are closed. to run your server you should either fix this or try to host your server somewhere(i believe you can get a three day trial on some of the servers, but then you'll have to pay, but it's like 5$/month)

well, there's much less problems if you want to play competitive and you all have steam version since you can create a server on fastcup and play(for free) on cs.fastcup.net you are actually able to create a room for them to join, so yeah

also, you can download radmin vpn(it's like hamachi but without tunnel or yellow triangle issues) and play through "new game"(but you'll have to write sv_lan 0 in console) AND through HLDS server, but ping...uhh... i guess it's gonna be a little high