How do I find the equations to solve this circuit

I need to find three equations in terms of v1, v2, and v4 and not sure how to approach this. I haven't done circuit analysis in two years and need some assistance with this. Thank you.

Here is a picture of the circuit.
http://img138.imageshack.us/img138/80/ci…

I suggest using nodal analysis
for node 1 (V1) The current into the node is 8 amps and the current out is (V1 - V2)/8 ohms. So
8 amps = (V1 - V2)/10 ohms
for node 2 (V2)
6Io current = (V2 -V1)/10 ohms + V2/4 ohms + (V2 -V3)/12 ohms
Where 6Io current is the current into V2 from the 6 Io voltage source.
But V3 = 20 Volts and V2 = 6Io + 20 Volts , so V2 - V3 = 6Io Volts

Node 4 (V4)
Io = 8 amps + V4/1 ohm
But 2Io = V4/1 ohm
The current through the 1ohm resistor is 2 Io
Io = 8 + 2Io
Io = 8/3 = 2.666 amps
So V4 = 2Io= 5.333 volts
The first equation can be written as
80 volts = V1 - V2 = V1- 6Io -20 and since 6Io = 6(2.666) = 16 volts
V1 = 100 + 16 = 116 volts
V3 is 20 volts
V2 = 20 + 6Io = 36 volts
So
V1 = 116 volts
V2 = 36 volts
V3 = 20 volts
and V4 =5.333 volts

You just want how?

Open your textbooks and look up the various laws of circuits, such as kirchoff's, ohm's, and others.

Time to refresh you knowledge of Thevenin and Norton: refer to the 'Net.