i have 10 pc at home and currently i have been using internet connection sharing using a modem, my lan is managed by a switch. though now i need to apply a router to to my network.
what is the best way to set it up?

Your router will be connected to your modem on the router's WAN port. You can connect the router to your switch on an uplink port or connect using a crossover cable If the switch or router cannot detect the port configuration automatically.

The internet router will have different config options to help you log into to your ISP via the router unless the modem takes care of the login process. These details simply depend on the modem and router. Should not be a big deal to make the connection.

thanks Jorge, though i want to use two different ISP, so how can i make it automatic when one connection goes down.

There are routers on the market that support this type of configuration (allow you to connect to more than one WAN connection). These routers take care of the automatic failover. Does your Internet router have this option? If so, what trouble are you having setting it up?

If you dont have this option, what else do you have to be able to connect to two ISPs?

For example, Cisco-Linksys RC042 supports dual external WAN connections. When the primary fails, the secondary kicks in and everything routes automagically.