Google this -> How to use a router as a WAP?
There are many versions of this so you can choose the one you like. I've never had to uplink or do anything special since this just works.
We have a leased line internet connection and a cisco 1841 router is being used for this which one is uplinked into a switch.
Now, we want to install Wi-fi router for sharing internet connection but bit confused how to set up i mean detail setup like which port would be uplinked between two reouters (cisco and wi-fi) and also how to connect to switch because we need wired lan as well wi-fi at same time depends on users choice.