Hi @n.yousra1,
Here are some links that can help you:
- http://www.gns3.net/documentation/
A great one that always works for me is GNS3Vault:
- http://gns3vault.com/labs/
This last one comes with hundreds of topologies and practices that you can try to do by yourself and they are categorized by technologies. You should try it!
Enjoy. HTH
Rgrds,
Martin, IT Specialist