I need a 24 port gigabit ethernet cisco switch with 2 fiber ports in gns3. An example of this switch is the Cisco SGE2000 switch, i found out that the gns3 only provides only their default etherswitch router which only provides fastethernet ports. So can i emulate a switch like cisco SGE2000 in gns3?
No you can't. It looks like newer versions of GNS3 support IOSvL2 (shipped with Cisco VIRL) and you now can setup many standard switch features (spanning-tree, LACP, port-security, ...). But this will not be like a standard 24 port switch running IOS.
And BTW: Cisco SMB Switches do not run IOS, they are quite different.