Hi processengineer1998,
I think that the real difficulty when you use OLGA is not how to set the input in the textual input or in the GUI, but how to correctly read and comprehend the outputs, especially when you work with multiphase fluids and transient state. Moreover, OLGA requires the knowledge of some tricks that sometime make the difference between a long and difficult simulation and a short and right one. Tricks and comprehension walk with the experience, but a basic course could be usefull to learn how to move the first steps.
PVTsim is quite different: since you mention PVTsim with OLGA I think that your preferential use of PVTsim is to built the fluid table to run OLGA ... in this case, if your fluids are well know (dry gas, for example) the use of PVTsim is quite simple. However, if you use fluid "more complicated" like gas condensate or oil and you need to tune the fluid's properties to match the field data, then you need experience and training course as base too.
Finally, I quote the answer of engmsh: both software have quite good help Guide and a quite good on-line help too.
Regards
Matt17
Process Engineer