Hello!
In order to give a PC internet from another one you need to either "Bridge" the connection, or share the connection. Bridging requires an ethernet cable, one ethernet slot free on one PC and another ethernet slot free on the PC you want to give connection to.
Sharing requires the PC you want to connect has a wireless card or dongle installed so that it can connect using wireless to the computer.
To bridge a connection, connect one computer to another via ethernet cable and go to control panel, network and sharing center, adapter settings, then select both connections that you can see, right click and select "Bridge connections".
To connect a computer wirelessly to another one, on the computer that has an internet connection go to control panel, network and sharing center, right click on the active connection, click on properties, then click on the tab "sharing" then click the tick box that says "Share this connection" or something like that (I forget, haven't done it in a while
)
I hope this helps!