yes, I've installed more memory and it should be pretty easy. If memory serves me, at the bottom of your imac below the screen, just above the foot in the bottom of the iMac's outer case, there's a little cover. Undoing that cover reveals 4 slots. The max memory you can install in your iMac is 16 gigs
(4 sticks of 4 gigs each). The only tool you should need is a phillips (cross point) screwdriver. It may help to rest the iMac on a pillow and be careful.
The type of memory is "DDR-3, 1333 Mhz SODIMM" , and is available from CanadaRam, MacSales, and other places. It's very important to know what kind of iMac you have for sure. some of 'em will take up to 32 gigs and some of 'em will only take 16 gigs maximum. IMHO, seeing as how the price is around $200, you might as well go for the most memory you can. the job should be done in as little as 20 minutes and yes, you can do it yourself. It'll be worth it !!
John B