parallel or series?

I'm a noob with electronics and never understood resistors and stuff till I started learning about lasers.
I'm running DDL's circuit without the pot and with 3 1 ohm resistors in place connected in series.
I was wondering, when using multiple resistors in this circuit, how does it affect it having the resistors connected in series or parallel?
I don't have a mulitimeter atm so havn't been able to test my outputs.

For building Lasers a DMM is more or less essential, they are pretty cheap and it means you can check your circuit before soldering your expensive LD in place.

You can pick meters up from ebay for the price of a couple of blown LD's.

An example of series/parallel using 2 X 10 ohm resistors

In parallel would give 5 ohms, in series would give 20 ohms, it becomes more complex when mixing values but there are calculators available on the web....Google is your friend.

Regards rog8811

Ok, thx, that helps to understand a bit. i've seen one of those calculators. I do have a DMM but it is only accurate past 400mv :S am looking for a new 1.

basically resistors in series mean the more you have the more resistance you get.
Resistors in parallel mean you will get less resistance the more resistance you put in..

something to do with : 1/Rt=1/R1 + 1/R2 + 1/R3

when parallel you can also count the rated wattage together e.g. if you have 2x 10ohm, 1/4w in parallel you'll get 5ohm,1/2w

and what's that wattage rating about for the resistors. my 10ohm resistors are 0.5W. so does that mean 2 on parallel gives 5ohm 1W?
Do I have to keep that wattage at a safe level?

you have to know how many watts are going through the resistors W=Volts*amps