Don't give up that easy, and welcome to the forum...
your amp as many new and old stereo units has pre and main jumpers..
heres a pic of them in
http://www.blackswampaudio.com/Images/Inv/1291.10.jpg
and heres a pic of them out
http://digilander.libero.it/pasqua49/COLLEZIONE HI-FI/MARANTZ 1060/Marantz 1060 back.jpg
That is where you will focus on integrating a subwoofer into your system...
Here is how..
Buy 2 pairs of rca splitters, and a pair of 70hz high pass fmods, and you pull the jumpers on the pre out and main amp out install the spiltters and the fmods going back to the main amp and install the other end of the splitters to the subwoofer...
But an easier way to do it and IMO a better way would be to buy a sub with a high pass output and run rca's from you pre out to your subs input, then your subs high pass output to your main amp input on your amp... {of course remove the jumpers..}
And the last way would be to get a mini DSP 2x4 and it go from pre out to the mini dsp and then out of the mini dsp to your amp and sub...
Its not just as easy as hooking in an amp, you want to make sure your mains no longer make the lows, so you want them to stop getting the frequencies, this will do a couple positive things, 1-the low are hard to reproduce and take a lot of power to do so from your main amp, SO this is going to free up you 60w for the mids and highs, very good idea and 2-Its a bad idea to have your sub and your mains overlapping the same sounds, its is not good for sound quality...
I am not sure what your mains are but crossing around 80hz is usually good for most... If you want to be able to adjust the cross point there are a couple ways to do this, 1-fmods, you can buy different fmods to high or low pass at different feq's and levels... 2 a controller or EQ, the minidsp works very well, is kind of detailed to get started since you need a pc to program it up, but its a nice system and for $105 I feel it does a lot...
here are some links for you to look at...
http://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4
http://www.svsound.com/subwoofers/sealed-box/sb-1000
http://www.svsound.com/specials/outlet-specials/sb12-nsd-outlet-c#.VAHBDfldWHg I would get the sb12nsd this one has no damage and is on closeout, that is an awesome price and its a good amount more sub than the 1000, plus it has the built in xover if you choose to go that route... this wont last the weekend on the site, they are on sale, and that is an awesome price for that sub....
PS- For music I like sealed subs, for your 60w mains, I would think the sb1000 and sb12nsd would be more than enough depending on your taste in music and level you listen at... Also dual subs are better than one, but one will fill your system a lot more than none...
I also drew you a picture to show you how to wire it...
For others searching this topic, if your amp does not have main and pre jumpers, then you still have a few options to add a subwoofer, 1 is to buy a sub with speaker level/high level inputs like the outlaw lfm's
http://www.soundandvision.com/images/archivesart/1206totem.3.jpg jbl, wharfedale, and many others have high level input and outputs...
Another way is to use a converter, not my favorite option but it will work...
http://www.amazon.com/AudioControl-2-Channel-Converter-Subwoofer-Control/dp/B004CTBYGE/ref=sr_1_3?ie=UTF8&qid=1409401898&sr=8-3&keywords=line+level+converter and then you need one of these to power it
http://www.amazon.com/supply-adapter-monitor-security-charger/dp/B00MHKBYB0/ref=sr_1_12?ie=UTF8&qid=1409401931&sr=8-12&keywords=12v+wall+wart there are much cheaper ones, but a friend of mine used this one an it worked well, you can get them as low as $5 on amazon, but I have no experience with them...
good luck...