[MA_proking]

how announce when somebody completes 5 hours

[DeathOnaStick]

Set a Timer using SetTimerEx (look in wiki for help), with an interval of (5*1000*60*60)milliseconds (=5hours). The announcement should be placed in the callback that is called when the timer 'waited' 5 hours.
Like I said, in the wiki you will find much help to it and it isnt that complicated.

Cheers.

[MA_proking]

Can you tell me full command

[Biesmen]

What? Just do what he said, convert his words into code language.

pawn Код:

forward FiveHours(playerid);

public OnPlayerSpawn(playerid)
{
    SetTimerEx("FiveHours", 18000000, true, "i", playerid);
    return 1;
}

public FiveHours(playerid)
{
    return SendClientMessage(playerid, -1, "You've been playing for 5 hours in a row!");
}

[MA_proking]

where I put it

[Biesmen]

Please learn this before you are going to continue scripting.
https://sampwiki.blast.hk/wiki/Scripting_Basics

After you learned it, we can talk.