On an other computer attached to your LAN:http://servername:4780/qmc/default.htm Replace servername with the name of the server that is running the QlikView Management Service.
Note that this information has been posted maybe a hundred times before in the community. The seach feature may not be your best option to find redundant information here, but Google is an extremely powerful tool to search the community. You should try it out.
As an afterthought: you may still be unable to open the QMC on your laptop/desktop. In that case, check the following:
Is your server allowing traffic to pass through port 4780 (by default disabled in Windows firewall)?
Is your Windows account a member of the local group 'QlikView Administrators' on your server?