you can visit the Singer website and download a pdf manual from there. Link is http://www.singerco.com/accessories/instruction-manuals
, type the manual number into the search field and click "search" then wait for the screen to build. There should be a red box "Download now" beside your model, click on this then again wait a while as the pdf file will be large. Once it opens to your screen you can save it to your PC, then print it out and bind or staple it up.
Threading a serger is completely different to a sewing machine and you will find a set of tweezers and a wire loop are invaluable. If these are not in your machine kit, then you should be able to buy from a sewing centre. You need to thread up in the sequence shown in the manual. For a four thread stitch this is probably upper looper, lower looper, then the two needles. But check the manual as it may be different on yours. Many sergers will have a threading diagram inside the front looper cover and this really helps until you get used to the machine. If you have cone holders in your kit put these onto the spool holders to keep the cones steady. Take the thread from the cone up to the aerial loop, down into the top loop, around the tension dial ensuring the thread has seated in correctly, then follow the threading guide down through the looper eyes and across to the stitching bed. Repeat for each thread path, then pull all four threads under the raised presser foot, lower the foot and chain off. Test stitch on fabric and look at the stitch, then adjust the tension dials for the loopers if needed. Needle tension shouldn't need changing usually.
Also check the manual to see if your model takes standard 130/704H needles, many do. But some sergers need a EL needle, its just a little longer. If you primarily plan to stitch knits on yours, then use ball point needles to stop stitches skipping. Otherwise sharps are fine, normally size 80 or 90. You won't need to change the needles as often as you do on your sewing machine but change if the stitch quality starts to go off.
And remember, always lift the aerial up to full height when you start to use the machine each time. The thread flows very fast through these machines and you need the aerial up high to give clearance for the cones so the thread can run off them smoothly.
Its a really good idea initally to thread up in 4 different thread colours and then you can diagnose the thread formation and see which thread to adjust tensions to get a good overlocked seam. Factory settings are usually 5 on all four tension dials but check your manual to double check this. Many times if you change colour thread, you can just knot on the new colour at the cone, turn the tension dial to zero then pull that thread through. This works fine for the loopers and on the needles, you just need to cut the knot off and thread the needle with the new colour. Then turn tensions back to normal setting, put the thread under the foot and chain off.
And if you do have a Singer dealership near you, perhaps see if they have a serger class as there is a few techniques that are so much easier to learn when shown; such as stitching into a right angle or turning an outside square corner and how to finish of the thread tails at the end of a seam.
There is also some good pages of info on the www.sewing.about.com
website, Debbie covers overlockers/sergers there and gives good photos and info as well as free projects.
I trust this helps you get started with your Singer Overlocker.