I want to Redirect multiple Sites in a single Irule. please help me with the irule command.

This irule will work. You may change it to fit for your need of multiple sites :

when HTTP_REQUEST { 
switch -glob [HTTP::host] {
 "hostname1" {
   HTTP::redirect "https://hostname1[HTTP::uri]
 }
 "hostname1" {
   HTTP::redirect "https://hostname1[HTTP::uri]
 }
 "hostname2" {
   HTTP::redirect "https://hostname2[HTTP::uri]
 }
 default { }
 }
}

If this is just for redirecting http to https, you can just use this irule :

when HTTP_REQUEST {
 HTTP::redirect "https://[HTTP::host][HTTP::uri]"
}

I have mulitple sites where i want my LAN users should not to redirected to https when they use url with http. but when any internet users use http://abc.com than it should redirect to https://abc.com

you may use IP::addr to check whether it is lan user traffic and then redirect if not.

e.g.

 config

[root@ve11a:Standby:In Sync] config  tmsh list ltm virtual bar
ltm virtual bar {
    destination 172.28.24.10:80
    ip-protocol tcp
    mask 255.255.255.255
    pool foo
    profiles {
        http { }
        tcp { }
    }
    rules {
        qux
    }
    source 0.0.0.0/0
    source-address-translation {
        type automap
    }
    vs-index 65
}
[root@ve11a:Standby:In Sync] config  tmsh list ltm rule qux
ltm rule qux {
    when HTTP_REQUEST {
  if { !([IP::addr [IP::client_addr] equals 172.28.24.0/24]) } {
    HTTP::redirect "https://[HTTP::host][HTTP::uri]"
  }
}
}

 test1 (client ip is 172.28.24.11)

[root@ve11a:Standby:In Sync] config  curl -I http://172.28.24.10/
HTTP/1.1 200 OK
Date: Wed, 20 Aug 2014 07:08:10 GMT
Server: Apache/2.2.3 (CentOS)
Last-Modified: Sun, 09 Feb 2014 08:39:51 GMT
ETag: "41879c-59-2a9c23c0"
Accept-Ranges: bytes
Content-Length: 89
Content-Type: text/html; charset=UTF-8

 test2 (client ip is 172.28.77.29) 

 curl -I http://172.28.24.10/
HTTP/1.0 302 Found
Location: https://172.28.24.10/
Server: BigIP
Connection: Keep-Alive
Content-Length: 0