there is package called AP-Hotspot in Ubuntu
1) Download AP-Hotspot Package from
http://www.ubuntuupdates.org/package/webupd8/raring/main/base/ap-hotspot
Double click over the package so that i will direct to software center,there you click install button and you will get password prompt for authentication,there enter the password
2) After installing go to terminal and type "sudo ap-hotspot configure"-Give Username and Password of your choice
3) Then type "sudo ap-hotspot start",Here you Go your Wifi-Hotspot is ready to share the network
4) To stop type "sudo ap-hotspot stop" command and to restart type "sudo ap-hotspot restart".