I have this banjo I bought about 3 or 4 years ago or more,but it's just a couple of months I actually took the decision of trying to play it properly.It's a 4-string banjo,but I don't know if it's a tenor banjo or a plectrum, banjo or what.I'm totally ignorant and I can't start to learn if I don't know what kind of banjo is.How can you know? It's the number of frets or what? Please help me! :)