How to connect PCs through cat5e/router connection ???

[akm]

PCs (desktop & laptop) connected with cat5e cables through router hub to internet connection (both see internet just fine).

Had them sharing folders with each other, but that recently went away (dont know why), and trying to re-establish that connection.

Can see desktop from laptop when click on 'My Network Places', but cant see same from desktop.

Have set 'shared folders' on both.

Have done 'Map Network Drive' from laptop, but when try at desktop, cant see any folders to select for laptop connection.

Is there a good source of info on how (step by step/s) to connect these 2 PCs with the existing hardwire connection ?