I'd start by reading the part of the manual for the Samsung phone which deals with using its facility to connect to a home wifi network.
Then have a look at the setup leaflet which came with your wireless router. Basically you could have issues between the phone and the router with:
(a) wireless mode
(b) wireless security type
(c) if you have turned on what's sometimes called Access List -- filters access to the router wifi, identifying users by their MAC ID.