Assigning IP addresses

[Jmacp]

Lots of network questions just now, thanks for all the help, sometimes you can get a clearer answer over a forum.

Say you have a LAN with 2 PC's connected to a router.

So do you always need to manually assign each PC an IP address and subnet mask, i thought this is what DCHP does ?

Even if DCHP does do that, is there always a set IP for PC number 1 on a network(and how do you even tell what PC 1 is), if you do assign an IP it's something like 192.168.1.1 then the next PC would be 192.168.1.2(??), is this always the case why do i see IP's like 10.0.0.1 as LAN IP's

Or do you have a good guide to point me to for this?