most of the available keyloaggers on the internet today are easily detected by Anti virus programs so it is best to write ur own keylogger program using some kind of antivirus evasion techniques but first before getting into all this learn a good programming language such as C or C++ althought it is much more simpler to learn python i would recommend learning a lower level language such as C,, once ur done with learning C check for works of proof of concept virus writing groups such "rrfl" to understand the various kinds of AV evasion techniques and implement them in ur program.