how to fit a solid bath panel

[nicebutdim]

Hello all ... I'm new to this so hope I've chosen the correct forum! I'm having problems deciding how to fit a solid MDF bath panel (end & side) with a separate plinth. I'm used to the more pliable kind of panel that just bends and slots neatly into place, so am at a bit of a loss where to begin and would really appreciate a few tips!