please don't take this as me being a dick, but...
maybe you should get a repair manual for the bike? that would, at the very least, help you identify the parts you are talking about, and give you some reference points as to what all is going on with the bike and what people on this site giving you advice are speaking about. seriously, every single bike i ever tear into at some point or another has some moment where i am elbow deep in engine parts saying to myself "what the hell is this?" moments like those, a shop manual can be worth its weight in gold. other times, shop manuals can also be just obscure enough to frustrate the hell out of you, but most of the time they are a very solid investment.
re the seals you are talking about, the shop guy was right - "the two seals on the left side of the bike." both of them can be replaced pretty easily, as has already been mentioned. if you are careful, you don't even have to drain the oil, just lay the bike on the right hand side and work on it there. there are also crankshaft seals, one on either side of the engine, they serve to keep the engine oil OUT of the crankcase, which is itself lubricated by the premix or autolube oil. they do need periodic replacement, and usually this involves tearing the engine almost all the way apart. they are in no way related to why your gearbox oil is appearing outside the engine instead of inside where it belongs.