welcome vasago to the world of vaping!
the nemesis is a awesome mod. depending on the batteries you got with the mod, you may want to look into better batteries. Most that come in kinds are terrible. best batteries for you buck would be sony's, efest, and aw imr's. rtdvapor or 101vapes would be my suggested place to look for good batteries. A lot of local shops often have a mix of good and bad batteries.
carto tank's are a very good place to start vaping. they have different ohm(resistance) that will give you various performance. Most stick with either 1.5ohm for a stronger hit on a mech or 3.0 for a smoother hit.
As far as juice for the carto tank's a vape shop that offers the oppurtunity to sample juice before you buy would be the easiest way. there are thousands of flavors and everyone likes something different. Just dont expect to have the exact taste of a cigarette, as much of the taste is given off by the burning of paper/leaves/chemicals. Once you find what you like you can always search for similar flavors online to expand your juice arsenal. as far as filling the carto tank youtube will give you awesome visual guides on filling.
hope you enjoy as much as many of us do