There are loads of ways to power and control fans. Which way you use depends on which fans they are, how many motherboard headers you have and if you wish to speed up and slow down the fans.
A lot of people use fan controllers which accept multiple fans plugged directly into it, allowing the user to control each fan's speed, either automatically in response to temperature variances or manually as desired.
If the fans have a Molex connector you can plug them into the PSU and have them run at 12v all the time.
You could plug directly into the motherboard if the fans are 3 pin and provided you have enough headers. Splitters can increase the number of fans you can plug in. Sometimes you'll get basic voltage control.
If they are PWM fans you could, through the use of PWM splitters, effect control over all your fans via the CPU temperature.
I've not installed a side fan but I'd probably set it up as intake to blow over a dual graphics card configuration and omit it if it were a single card configuration.
Pretty basic stuff though for any PC builder. I take it your forum name is not wholly accurate.
